Layered absorbent structure

ABSTRACT

A distinctive absorbent article includes an absorbent core having multiple absorbent layers, wherein the absorbent layers interact in such a manner which preferentially locates absorbed liquid in an appointed, high saturation wicking layer. The localization of the liquid within this wicking layer increases the potential of this layer to move liquid through capillary action due to the higher saturation level and increased amount of liquid available. The intake capability of the absorbent system is maintained or improved over current systems by keeping a second layer of the absorbent system at low saturation levels through as many insults of the product as possible, while providing optimum intake performance through appropriate control of the composite properties. The low saturation in this layer provides void volume for the incoming insult as well, as a high permeability, thus increasing the intake rate of the absorbent system as a whole, but the structure of the low saturation layer is also balanced to provide an appropriately high level of capillary tension to provide enough control of the liquid to stop leakage from occurring. This low saturation layer is used in addition to a surge material and provides intake functionality in addition to that provided by the surge material. In particular aspects of the invention, the body side layer of the absorbent core does not extend over the entire surface of the overall absorbent core, therefore is not used as the high saturation, wicking layer, but as the intake layer. This arrangement also allows the intake layer to be in direct contact with the incoming liquid, therefore allowing for more immediate access and improved intake function.

This application is a continuation-in-part application claiming thebenefit of: U.S. application Ser. No. 09/096,652 entitled LAYEREDABSORBENT STRUCTURE and filed in the U.S. Patent and Trademark Office onJun. 12, 1998, now abandoned; U.S. Provisional Application Ser. No.60/062,173 entitled LAYERED ABSORBENT STRUCTURE and filed on Oct. 16,1997, in the names of Rob D. Everett, et al. (attorney docket No.13505.1), now abandoned; U.S. Provisional Application Ser. No.60/061,450 entitled LAYERED ABSORBENT STRUCTURE and filed on Oct. 8,1997, in the names of Rob. D. Everett, et al. (attorney docket No.13505), now abandoned; U.S. Provisional Application Ser. No. 60/062,174entitled LAYERED ABSORBENT STRUCTURE WITH A ZONED BASIS WEIGHT and filedon Oct. 16, 1997, in the names of Rob D. Everett, et al. (attorneydocket No. 13,506.1), now abandoned; U.S. Provisional Application Ser.No. 60/061,452 entitled LAYERED ABSORBENT STRUCTURE WITH A ZONED BASISWEIGHT and filed on Oct. 8, 1997, in the names of Rob D. Everett, et al.(attorney docket No. 13,506 now abandoned); U.S. Provisional ApplicationNo. 60/062,190 entitled LAYERED ABSORBENT STRUCTURE WITH A HETEROGENEOUSLAYER REGION and filed on Oct. 16, 1997, in the names of Rob D. Everett,et al. (attorney docket No. 13,507.1), now abandoned; U.S. ProvisionalApplication Ser. No. 60/061,376 entitled LAYERED ABSORBENT STRUCTUREWITH A HETEROGENEOUS LAYER REGION and filed on Oct. 8, 1997, in thenames of Rob D. Everett, et al. (attorney docket No. 13,507), nowabandoned; U.S. Provisional Application Ser. No. 60/062,189 entitledLAYERED ABSORBENT STRUCTURE WITH A ZONED BASIS WEIGHT AND AHETEROGENEOUS LAYER REGION and filed on Oct. 16, 1997, in the names ofRob D. Everett, et al. (attorney docket No. 13,508.1), now abandoned;and U.S. Provisional Application Ser. No. 60/061,416 entitled LAYEREDABSORBENT STRUCTURE WITH A ZONED BASIS WEIGHT AND A HETEROGENEOUS LAYERREGION and filed on Oct. 8, 1997, in the names of Rob D. Everett, et al.(attorney docket No. 13,508), now abandoned. The entirety of applicationSer. Nos. 09/096,652; 60/062,173; 60/061,450; 60/062,174; 60/061,452;60/062,190; 60/061,376; 60/062,189; 60/061,416 are hereby incorporatedby reference.

FIELD OF THE INVENTION BACKGROUND OF THE INVENTION

Performance objectives of disposable absorbent articles, such as infantdiapers, include no product leakage, dry feel to the wearer, and acomfortable fit throughout the product life. Accordingly, absorbentarticles typically contain an absorbent core to provide liquid handlingand other absorbent functionalities required to meet the productperformance objectives. The absorbent core of absorbent articles iscommonly composed of wood pulp fibers, and superabsorbent material isoften distributed in the absorbent core to enhance the liquid absorbentcapacity. The absorbent core is usually formed in an hourglass,T-shaped, or similar configuration with reduced absorbent width in thecentral crotch region for wearer fit and comfort.

Absorbent articles frequently leak before the liquid absorbent capacityof the entire absorbent core is fully utilized. One problem resulting inleakage is the inability of the absorbent core to fully uptake liquidsrapidly and completely when large amounts of liquids are discharged intothe absorbent article. Another associated problem contributing toleakage is the inability of the absorbent core to move or distributesufficient amounts of liquid between discharges from a target areaportion of the absorbent article to more distal and more remote endregions of the absorbent core which have not been utilized. This resultsin saturation of only the central target area of the absorbent core andexcessive thickness, bulkiness, and sagging of the wet, heavy absorbentmaterial resulting in poor performance, product fit and wearerdiscomfort. These absorbent core deficiencies are especially acute forthin, narrower-crotch absorbent designs having a crotch width of lessthan about 4 inches that provides less absorbent mass and bulk in thetarget area for improved product fit.

The absorbent core of current absorbent articles does not adequatelymeet current performance objectives. The desirable absorbent core liquiduptake and distribution functionalities required for upstream narrowercrotch higher efficiency absorbent article designs is also beyondcurrent capabilities. Consequently, there remains a need for absorbentstructures which can provide improved fluid uptake of liquid insults andimproved liquid distribution to move liquid out of the target areabetween liquid insults to maintain this desirable liquid uptake behaviorfor the life of the product.

BRIEF DESCRIPTION OF THE INVENTION

The disclosed invention is an absorbent system which includes multipleabsorbent layer regions. The two or more absorbent layer regions canadvantageously interact in a manner which preferentially locates anappointed liquid in a selected layer region. This localization of theliquid within this layer region can increase the potential of this layerregion to move liquid through capillary action due to the highersaturation level and increased amount of liquid available. The intakecapability of the absorbent system can be maintained or improved overcurrent systems by keeping a layer region of the absorbent system at lowsaturation levels through as many insults of the product as possible,while providing optimum intake performance through appropriate controlof the composite properties. The low saturation in this layer regionprovides void volume for the incoming insult as well as a highpermeability, thus increasing the intake rate of the absorbent system asa whole. The properties of this layer region can advantageously bebalanced with an appropriately high level of capillary tension toprovide enough control of the liquid to substantially stop undesiredleakage. This low saturation layer region can be used in addition to alayer of surge management material and can provide an intakefunctionality in addition to that provided by the surge material. Inparticular aspects of the invention, a body side layer of the absorbentstructure may not extend over the entire surface of the absorbentsystem, and may be configured to provide an intake layer portion whichis additional to the high saturation, wicking layer region. Thisarrangement can locate the intake layer region to be in a substantiallydirect contact with the incoming liquid, and thereby allow a moreimmediate access to the incoming liquid and an improved, liquid intakefunction.

In other aspects of the invention, the layer regions of the absorbentsystem can cooperate to provide a desired Liquid Wicking Potentialvalue, such as a Liquid Wicking value of at least a minimum of about 16%The invention can also provide a desired Flow Conductance Value, such asa Flow Conductance Value of at least about 7*10⁻⁶ cm³. In additionalaspects, the invention can provide a combined Conductance-Wicking valueof at least about 14*10⁻⁶ cm³. Further aspects of the invention canprovide a system which provides the desired Flow Conductance Value andalso includes at least one layer region having the desired LiquidWicking Potential value. Still other aspects of the invention caninclude superabsorbent polymer (SAP) material which exhibits aparticular controlled absorbency rate. For example, a desiredcontrolled-rate superabsorbent can exhibit a particular absorbency rate,Tau value, such as a Tau value of at least about 0.67 min. In additionalaspects, the invention can include a combination of superabsorbentmaterials which have a particular ratio of Tau values.

In its various aspects, the present invention can provide an articlehaving a more efficient absorbent structure which is thin with low bulk,has high absorbent capacity, and is resistant to leakage. Theconfigurations of the invention can more fully utilize the totalpotential absorbent capacity of the absorbent structure, and can moreefficiently move and distribute acquired liquid away from the originalintake area to more remote areas which are located closer to the distalend regions of the absorbent structure. In addition, the structures ofthe invention can provide an ability to acquire and intake liquid at arapid rate, and can maintain the desired intake rate after the absorbentstructure has been wetted and has reached a significant portion of itspotential, total absorbent capacity.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood and further advantages willbecome apparent when reference is made to the following detaileddescription of the invention and the drawings, in which

FIG. 1 representatively shows a top view of an absorbent article whichincorporates an absorbent system of the invention;

FIG. 1A representatively shows a lateral, cross-sectional view of thearticle of FIG. 1;

FIG. 1B representatively shows a longitudinal, cross-sectional view ofthe article of FIG. 1;

FIG. 2 representatively shows a top view of the structure of anabsorbent core of the invention having a first, top layer region whichextends over a medial portion of the total area of the absorbent core,and a second, bottom layer region which extends over substantially theentire area of the absorbent core, where the opposed, longitudinal endedges of the first layer region are spaced from each of the opposed,longitudinal end edges of the second layer region;

FIG. 2A representatively shows a longitudinal cross-sectional view ofthe absorbent core of FIG. 2;

FIG. 3 top view of another absorbent core structure of the inventionhaving a first, top layer region which extends over a medial portion ofthe total area of the absorbent core, and a second, bottom layer regionwhich extends over substantially the entire area of the absorbent core,where the second layer region has a non-uniform, zoned basis weightdistribution with a relatively greater basis weight at itslongitudinally opposed end portions to provide a longitudinal reversezoning of the lower layer;

FIG. 3A representatively shows a longitudinal cross-sectional view ofthe absorbent core of FIG. 3, wherein a selected medial portion of thesecond layer region has a basis weight which is lower than that of theadjacent, longitudinally opposed end portions of the second layer toprovide a reversed zoned basis weight of the second layer in the targetarea;

FIG. 4 representatively shows a top view of another absorbent corestructure having a top layer region which covers an entire front portionof the bottom layer region, but covers less than the entire back portionof the bottom layer region;

FIG. 4A representatively shows a longitudinal cross-sectional view ofthe absorbent core of FIG. 4;

FIG. 5 top view of another absorbent core structure having a top layerregion which entirely covers a bottom layer region;

FIG. 5A representatively shows a longitudinal cross-sectional view ofthe absorbent core of FIG. 5;

FIG. 6 representatively shows a top view of another absorbent core witha top layer region which has both a lesser, narrower lateral dimensionand a lesser, shorter longitudinal dimension than the bottom layerregion;

FIG. 7 representatively shows a longitudinal, cross-sectional view of anabsorbent core of the invention which includes a bottom layer regioncomposed of a laminate having superabsorbent particles sandwiched andheld between layer regions of liquid permeable material;

FIG. 8 representatively shows a longitudinal, cross-sectional view ofanother absorbent core of the invention which includes a second, bottomlayer region composed of a plurality of heterogeneous, sublayerlaminates arranged to provide a nonuniform, zoned basis weight withinthe bottom layer region;

FIG. 9 representatively shows a longitudinal, cross-sectional view ofanother absorbent core of the invention which includes a bottom layerregion composed of a heterogeneous laminate wherein the distribution ofsuperabsorbent material is arranged to provide a nonuniform, zoned basisweight of superabsorbent within the bottom layer region;

FIG. 10 shows a schematic representation of a testing apparatus fordetermining particular properties of a superabsorbent material;

FIG. 11 shows a representative cross-sectional view of a cylinder groupplaced in a basin with a weight applied onto a piston disk;

FIG. 12 shows a representative cross-sectional view of a cylinder groupplaced in a basin with a piston rod positioned for tapping against apiston disk;

FIG. 13 shows a representative cross-sectional view of a cylinder groupwith a weight applied onto a piston disk, and placed on a vacuumfixture;

FIG. 14 shows a representative cross-sectional view of a cylinder groupplaced on a vacuum fixture.

DETAILED DESCRIPTION OF THE INVENTION

The various aspects and embodiments of the invention will be describedin the context of a disposable absorbent article, such as a disposablediaper. It is, however, readily apparent that the present inventioncould also be employed with other articles, such as children's trainingpants; feminine care articles, incontinence garments, protective coverpads and the like, which may be configured to be disposable. Typically,disposable articles, such as disposable garments, are intended forlimited use and are not intended to be laundered or otherwise cleanedfor reuse. A disposable diaper, for example, is discarded after it hasbecome soiled by the wearer. In the context of the present invention, amechanical fastening system is a system which includes cooperatingcomponents which mechanically inter-engage to provide a desiredsecurement.

The present invention provides an absorbent system having an absorbentcore which includes multiple, layer regions and can providesignificantly improved void volume, permeability, and liquid-intakeperformance in an appointed target region. The absorbent system,particularly an absorbent core portion of the system, can substantiallyregenerate the desired levels of void volume through a transport of theliquid out of the target region, such as by wicking or other mechanisms.The liquid can advantageously be concentrated in the layer region of theabsorbent core which is appointed to provide the desired, relativelyhigh distribution of liquids, while the layer region appointed toprovide void volume and intake can remain relatively low in saturation.In most cases the relative basis weights or superabsorbentconcentrations of the layer regions can be configured and arranged sothat suitably cooperating materials with the appropriate properties willbe able to work in the system and provide good performance. It has beenfound, however, that particular combinations can provide significantlyimproved performance over others. It should also be noted that the basisweights or other properties of the components may be modified inspecific areas of the absorbent structure (e.g.; front vs. back) tooptimize cost, other consumer attributes, or to promote desireddistributions of the absorbed liquid.

In the present invention, the absorbent layer regions can bedistinctively configured to cooperatively interact in a manner whichpreferentially locates liquid in one or more designated or appointedlayer regions. This localization of the liquid within a designated,layer region can increase the potential of this layer region to move anddistribute liquid through capillary action, due to the relatively highersaturation level and increased amount of liquid available in thedesignated layer.

The intake capability of the absorbent system, particularly the intakecapability of the absorbent core, can be maintained or improved overconventional systems by keeping a primary, intake layer region of theabsorbent system at low saturation levels through as many insults of theproduct as possible, while providing optimum intake performance throughappropriate control of the composite properties. The relatively lowlevel of liquid saturation in this intake layer region provides voidvolume for the incoming insult as well as a high permeability, thusincreasing the intake rate of the absorbent system as a whole. Theintake layer region can advantageously be configured to provide anappropriately high level of capillary tension to adequately control ofthe movement of liquid and substantially avoid undesired leakage. Thislow saturation, intake layer region is desirably employed in addition toa separately provided surge management portion or layer, and can providean intake functionality which is additional to that provided by thematerial of the surge layer.

In particular configurations, the intake layer region can be located onthe body side of the absorbent structure, and can be configured to notextend over the entire area expanse of the total, overall absorbentstructure. Accordingly, the primary, body side layer region is employedas an intake layer region, and is not employed as the high saturation,wicking layer region. This arrangement also allows the intake layerregion to be in a substantially direct contact with the incoming liquid,thereby allowing for a more immediate access to the incoming liquid anda more effective intake function.

The layer regions can be designed, individually or in combination, toprovide an improved balance of intake and distribution functions,particularly the intake and distribution of aqueous liquids. Theimproved performance can, for example, be provided by modifying thephysical and/or chemical composition of the component materials or bymodifying the physical configurations of the components.

Current fiber and superabsorbent polymer (SAP) composites used inconventional designs of absorbent article, such as diapers, can provideordinary combinations of intake, distribution, and retention functions.There has, however, been a continued need for improved materials andimproved systems and structures which provide improved combinationshaving increased levels of the intake, distribution and retentionfunctions. To provide improved leakage resistance, the present inventionincorporates improved materials, where the materials exhibit improvedproperties in at least one of the functional areas. As a result, theoverall performance of the system can be improved.

The intake function can, for example, be adjusted by controlling factorssuch as the fiber and particle sizes of the materials in the relevantlayer region, the layer-region porosity, the layer-region basis weight,and the layer-region composition. The distributing or distributionfunction can, for example, be adjusted by controlling factors such asthe fiber and particle sizes of the component materials, the liquidcontact angles provided for by the materials, the liquid surfacetensions provided by the liquid, and the basis weights of the materials.

To further improve the desired balance of absorbent properties, therehave been identified a number of important factors which can allow thelayer regions to better work in combination, and thereby provide animproved overall system performance. The factors include a desired FlowConductance Value and a desired Liquid Wicking Value provided by theabsorbent system. An additional factor is a combined Conductance-Wickingvalue provided by the system.

The Flow Conductance is a value which is based on the physicalproperties of the absorbent materials, particularly the absorbentmaterials which are disposed in the target area of the absorbent system,and is related to the intake capability provided by the absorbent corestructure. Desirably, the Flow Conductance Value has a minimum of notless than about 2.5*10⁻⁶ cm³. Alternatively, the Flow Conductance Valueis not less than 3*10⁻⁶ cm³, and optionally, is not less about 3.5*10⁻⁶cm³ to provide improved performance. In further aspects of theinvention, the Flow Conductance Value can be up to about 5*10⁻⁶ cm³.Alternatively, the Flow Conductance Value can be up to about 7*10⁻⁶ cm³,and optionally, can be up to about 9*10⁻⁶ cm³, or greater to provideimproved performance.

The Liquid Wicking Potential value (or Liquid Wicking Value) is aperformance parameter which pertains to the amount of liquid removedfrom a described target area of the absorbent structure during avertical wicking operation. This value represents the ability of theabsorbent structure to remove fluid from the target area betweeninsults, and at least one layer region of the absorbent system isconfigured to provide the desired Liquid Wicking Value. Desirably, atleast one layer of the absorbent system, particularly at least oneprimary layer region of the absorbent core, can provide a Liquid WickingValue of not less than a minimum of about 10%. Alternatively, theprovided Liquid Wicking Value is not less than about 15% and optionally,is not less than about 20% . In further aspects of the invention, theabsorbent system can provide a Liquid Wicking Value of up to about 60%.Alternatively, the provided Liquid Wicking Value can be up to about 65%,and optionally, can be up to about 70% or greater to provide furtherimproved performance.

The Combined Conductance-Wicking value (C) of the system can be at leastabout 14*10⁻⁶ cm³. Alternatively, the Combined Conductance-Wicking valuecan be at least about 16*10⁻⁶ cm³, and optionally can be at least about18*10⁻⁶ cm³ to provide an improved balance of performance.

In thin absorbent designs with narrow crotch sections, the target areaof the product, in its dry state, ordinarily does not have enough voidvolume available to efficiently absorb the initial insult of liquid,such as urine. This lack of void volume can be compensated for byincorporating a particularly configured SAP in an amount sufficient toabsorb the incoming liquid during the time of the insult. Theincorporated SAP is configured to acquire and hold the amount of fluidwhich is to be absorbed during the insult to provide the desired leakageresistance.

Although some of these parameters have individually been discussed inthe past, it is has remained difficult to provide an effectivecombination of these attributes within a single composite structure,while maintaining desirable consumer attributes. The difficulties facedin the past have typically involved a desire to have a relatively lowSAP content, either in the entire structure or within an individuallayer, to enhance wicking capability. Where the low SAP concentration isused throughout the product, an excessively large product thickness maybe needed to provide the desired absorbent capacity. Attempts have beenmade to provide one absorbent layer with a low SAP concentration topromote wicking, while maintaining high SAP concentrations in anotherother layer to achieve a thin product having the desired amount ofabsorbent capacity. Such systems have not provided the desired levels ofperformance because the liquid can preferentially move into the areascontaining relatively higher concentrations of SAP. In the layer regioncontaining the relatively low concentration of SAP, the amount ofremaining liquid can be insufficient to provide the desired levels ofwicking.

To overcome these shortcomings, a particular aspect of the invention caninclude a controlled-rate SAP in the absorbent system. Through the useof a controlled-rate SAP, such as a selected, attenuated rate SAP, theconcentration of liquid in a fibrous structure of appointed distributinglayer region can be kept high even when the distributing layer regioncontains selected amounts of SAP. In particular arrangements, thecontrolled slow-rate SAP is primarily located in a layer region which isother than the distributing layer. As a result, the low SAP layer canselectively become saturated, while the overall absorbent capacitywithin a thin product design is maintained at a desired high level. Itis contemplated that alternative mechanisms, other than theincorporation of the slow rate SAP, may be used to provide the desiredapportioning and differences in the concentrations of the absorbedliquid between the selected layer regions. For example, the desiredapportioning may be generated by selectively configuring the relativewettability and/or density of the layer regions.

With reference to FIGS. 1 and 2, an absorbent composite system 26 of theinvention includes a surge management portion 84, and an absorbent pador core structure 30. The absorbent core 30 has multiple absorbent layerregions, and the properties of the individual layer regions are selectedand arranged to provide improved leakage performance by balancing theintake and wicking properties of the absorbent components.

Generally stated, the absorbent core 30 of the present description,begins at the first layer which includes superabsorbent (as determinedwhen moving from the innermost, bodyside surface of the article towardsthe outermost surface of the article), along with any immediatecomponent needed to maintain the integrity of such layer duringfunctional testing. Such first layer desirably includes a minimum of notless than about 5 wt % superabsorbent. The absorbent core ends at thelast absorptive layer which is positioned immediately prior to thesubstantially liquid-impermeable layer which is appointed for preventingleakage from the diaper, as determined when moving from the innermost,bodyside surface of the article towards the outermost surface of thearticle. Accordingly, the absorbent core 30 of the shown configurationsincludes the first primary absorbent layer 48, the outermost layer ofwrapsheet 28, and the components sandwiched therebetween. The absorbentcore of the illustrated configuration excludes the topsheet layer 24,the surge management layer 84 which does not contain superabsorbent, andthe backsheet layer 22.

The appropriate balance of intake and wicking properties can berepresented by various determining factors, such as the Flow ConductanceValue, Wicking Value, basis weight, density, particle size, fiber size,relative amount of fiber, and the like, as well as combinations thereof.The Flow Conductance Value of the absorbent relates to the availablevoid volume and permeability of the structure throughout the varioussaturation levels typically encountered during ordinary use. To provideimproved performance for the absorbent system, the liquid should beallowed to enter the absorbent structure at a rate which is as near aspossible to the rate at which the liquid is delivered onto the absorbentcomposite structure. The Flow Conductance Value can help characterizethe intake potential of the overall, absorbent system 26, and canparticularly help characterize the intake potential of the absorbentcore 30. In addition, it is important to move the liquid away from theentry area for storage in more remote areas of the absorbent system tothereby recondition and prepare the entry area to more efficientlyreceive the next insult of liquid. The Liquid Wicking Value can helpcharacterize the ability of the absorbent structure to remove fluid fromthe entry, target area between insults.

With reference to FIGS. 2 and 2A, the absorbent core 30 has an overallcomposite core length 66, an overall composite core width 68, an overallcomposite core thickness 70, a crotch core width 58 and an appointedfront-most edge. The front-most edge is appointed for placement in afront waistband section of the article. The overall composite assemblyof the absorbent core 30 extends over and covers an overall core area,as illustrated in FIG. 2. The individual core component layers andoptional sublayers may extend over the entire absorbent core area, ormay extend over a selected portion of the core area, as desired toprovide desired performance. In addition, each of the individual layerregions has individual dimensions. In the representatively shownarrangement, for example, a first layer region 48 has a first thicknessor height 72, a first length 73 and a first width 74. A second layerregion has a second thickness or height 75, a second length 66 and asecond width 68.

With respect to the overall length 66 of the absorbent core 30, theintended intake, target area 52 of the absorbent structure is a regionof the absorbent core which begins at a laterally extending,cross-directional line located 24% of the length of the absorbentcomposite core length 66 away from a terminal, front-most edge of theabsorbent core, and extends to a cross-directional line located 59% ofthe absorbent composite length away from the front-most edge of theabsorbent core. In the illustrated arrangement, for example, the targetarea of the absorbent core can be an area of the absorbent structurewhich begins at a laterally extending line located approximately 3.5inches (89 mm) from the terminal, front-most edge of the absorbent coreand extends to a laterally extending line located approximately 8.5inches (216 mm) from the front-most edge of the absorbent core.

It has been undesirable to increase the Flow Conductance Value byincreasing the bulk of the absorbent core structure, because the productthickness can become excessive in articles having a narrow crotch width.As a result, there has been a continuing need for configurations whichcan provide the desired intake performance, such as represented by theFlow Conductance Value, while maintaining a thin absorbent core 30 and athin absorbent system 26. Desirably, the total thickness of the dryabsorbent core 30 is not more than about 6 mm. Alternatively, thethickness of the absorbent core can be not more than about 5.3 mm, andoptionally, the thickness of the absorbent core can be not more thanabout 5 mm to provide desired benefits. In another aspect of theinvention, the thickness of the dry absorbent core 30 can be not morethan about 25% of the crotch width of the absorbent core. Alternatively,the dry absorbent core thickness can be not more than about 20% of thecrotch width of the absorbent core, and optionally, can be not more thanabout 15% of the crotch width of the absorbent core to provide improvedbenefits. For the purposes of the present disclosure, the crotch widthof the absorbent core is determined at a narrowest (smallest) lateraldimension of the crotch region located within the target area 52 of thecore.

Desirably, the overall total thickness of the dry absorbent system 26 isnot more than about 8 mm. Alternatively, the thickness of the absorbentsystem can be not more than about 7.3 mm, and optionally, the thicknessof the absorbent system can be not more than about 7 mm to providedesired benefits. In another aspect of the invention, the overallthickness of the dry absorbent system 26 can be not more than about 30%of the crotch width of the absorbent system. Alternatively, the dryabsorbent core thickness can be not more than about 25% of the crotchwidth of the absorbent system, and optionally, can be not more thanabout 20% of the crotch width of the absorbent system to provideimproved benefits.

For the purposes of the present disclosure, the dry thickness ismeasured at a restraining pressure of 0.2 psi (1.38 KPa).

In a further aspect of the invention, the low bulk absorbent system 26,and particularly the absorbent core 30, can have a crotch region 54appointed for placement between a wearer's legs wherein a narrowest(smallest) lateral dimension of the crotch region located within thetarget area 52 provides a minimum crotch width 58. Accordingly, an adultproduct (intended for use by a person over the age of 13 years), canhave a crotch width the minimum lateral dimension of which is not morethan about 5.5 inches (about 14 cm) when the absorbent composite is dry.Alternatively, the minimum crotch width 58 can be not more than about4.5 inches (about 11.4 cm), and optionally can be not more than about3.5 inches (about 8.9 cm) to provide improved fit and comfort. Anon-adult product (intended for use by a person of age 13 years orless), can have a crotch width the minimum lateral dimension of which isnot more than about 4 inches (about 10 cm) when the absorbent compositeis dry. Alternatively, the minimum crotch width 58 can be not more thanabout 3 inches (7.6 cm), and optionally can be not more than about 2inches (5.1 cm) to provide improved fit and comfort for the non-adultpersons.

It is also important to remove liquid from the target area 52 of theabsorbent system to effectively avoid an over-saturation of this areaand leakage from the article. The ability of the absorbent system tomove liquid away from the target region can be represented by the LiquidWicking Value provided by the system. The Wicking Value is related tothe amount of liquid which the system is capable of moving out of thetarget area when the target area has a liquid loading/saturation levelof 1.0 gram of liquid per square centimeter of the target area of theabsorbent composite. Therefore, the present invention provides adistinctively layered absorbent system which is thin, is narrow in thecrotch region and exhibits low bulk.

The layer regions in the absorbent system are arranged to include abodyside first layer region which can be of various suitableconfigurations, but typically has a size which is no larger than thesize of the outermost, second absorbent layer region. This first, upperlayer region can maintain a low saturation level throughout the use ofthe absorbent article, and can maintaining a high Flow Conductance Valuewhen used in combination with the, second, lower layer region. The lowerlayer region can be selectively shaped, such as with an hourglass or “T”configuration, and is configured to efficiently distribute and moveliquid out from the target area of the absorbent composite. Inparticular, the second, lower layer region is capable of providing thedesired values of Liquid Wicking Potential, as can be determined by theLiquid Wicking Potential Value procedure described hereinbelow.

With reference to FIGS. 1, 1A and 1B, the invention can provide anabsorbent garment article, such as a diaper 20, having a longitudinal,length-wise direction 86, and a lateral, cross-wise direction 88. Thearticle has a first waistband section, such as rear waistband section40, a second waistband section, such as front waistband section 38, andan intermediate section 42 which interconnects the first and secondwaistband sections. The front waistband section 38 has a laterallyopposed, front pair of side edge regions 118, the rear waistband section40 has a laterally opposed, rear pair of side edge regions, 116, and theintermediate section 42 provides an article crotch region for placementbetween a wearer's legs.

FIG. 1 is a representative plan view of the representative disposablediaper 20 of the present invention in its flat-out, uncontracted state(i.e., with substantially all elastic induced gathering and contractionremoved). Portions of the structure are partially cut away to moreclearly show the interior construction of the diaper article, and thebodyside surface of the diaper which contacts the wearer is facing theviewer. The outer edges of the diaper define a periphery withlongitudinally extending side edge margins 110 and laterally extendingend edge margins 112. The side edges define leg openings for the diaper,and optionally, are curvilinear and contoured. The end edges are shownas straight, but optionally, may be curvilinear.

A liquid permeable topsheet layer 24 is superposed in facing relationwith a backsheet layer 22, and the absorbent system is operablyconnected and affixed between the backsheet layer 22 and topsheet layer24. The representatively shown configuration has an absorbent compositesystem 26 which includes a surge management portion 84 and a retentionportion for holding and storing liquid. The retention portion of theillustrated absorbent system includes the absorbent core 30. In theshown configuration, the surge management portion 84 is a layerpositioned between the absorbent core 30 and the topsheet layer 24.Other arrangements may also be employed. For example, the surge layer 84may optionally be positioned between the absorbent core and thebacksheet layer 22, or on the bodyside surface of the topsheet.

The article typically includes elastomeric members, such as leg elastics34 and waist elastics 32, and the surge management portion is positionedin an operative liquid communication with the retention portion of theabsorbent article. The topsheet 24, backsheet 22, absorbent core 30,surge management portion 84 and elastic members 34 and 32 may beassembled together into a variety of well-known diaper configurations.The diaper can additionally include a system of containment flaps 82,and side panel members 90 which may be elasticized or otherwise renderedelastomeric.

Examples of articles which include elasticized side panels andselectively configured fastener tabs are described in U.S. patentapplication Ser. No. 168,615 of T. Roessler et al., entitled DYNAMICFITTING DIAPER, and filed Dec. 16, 1993 (attorney docket No. 10,961),which corresponds to PCT publication WO 95/16425 dated Jun. 22, 1995.Various techniques for forming the desired fastening systems aredescribed in U.S. Pat. No. 5,399,219 of T. Roessler et al., entitledMETHOD FOR MAKING A FASTENING SYSTEM FOR A DYNAMIC FITTING DIAPER andissued Mar. 21, 1995 (attorney docket No. 11,186); in U.S. patentapplication Ser. No. 286,086 of D. Fries, entitled A PROCESS FORASSEMBLING ELASTICIZED EAR PORTIONS and filed Aug. 3, 1994 (attorneydocket No. 11,169) which issued as U.S. Pat. No. 5,540,796; and in U.S.patent application Ser. No. 08/415,383 of D. Fries, entitled AN ASSEMBLYPROCESS FOR A LAMINATED TAPE and filed Apr. 3, 1995 (attorney docket No.11,950) which issued as U.S. Pat. No. 5,595,618. The disclosures of theabove-described documents are incorporated herein by reference in amanner that is consistent (not in conflict) herewith.

Diaper 20 generally defines the longitudinally extending lengthdirection 86 and the laterally extending width direction 88, asrepresentatively shown in FIG. 1. The diaper may have any desired shape,such as rectangular, T-shaped, a generally hourglass shape, or aT-shape. With the T-shape, the crossbar of the “T” may comprise thefront waistband portion of the diaper, or may alternatively comprise therear waistband portion of the diaper.

The topsheet 24 and backsheet 22 may be generally coextensive, and mayhave length and width dimensions which are generally larger than andextend beyond the corresponding dimensions of the absorbent structure 26to provide for the corresponding side margins 110 and end margins 112which extend past the terminal edges of the absorbent structure. Thetopsheet 24 is associated with and superimposed on the backsheet 22,thereby defining the periphery of the diaper 20. The waistband regionscomprise those portions of the diaper, which when worn, wholly orpartially cover or encircle the waist or mid-lower torso of the wearer.The intermediate, crotch region 42 lies between and interconnects thewaistband regions 38 and 40, and comprises that portion of the diaperwhich, when worn, is positioned between the legs of the wearer andcovers the lower torso of the wearer. Thus, the intermediate crotchregion 42 is an area where repeated surges of liquid typically occur inthe diaper or other disposable absorbent article.

The backsheet 22 can typically be located along an outer-side surface ofthe absorbent composite 26 and may be composed of a liquid permeablematerial, but desirably comprises a material which is configured to besubstantially impermeable to liquids. For example, a typical backsheetcan be manufactured from a thin plastic film, or other flexible,substantially liquid-impermeable material. As used in the presentspecification, the term “flexible” refers to materials which arecompliant and which will readily conform to the general shape andcontours of the wearer's body. Backsheet 22 prevents the exudatescontained in absorbent composite 26 from wetting articles, such asbedsheets and overgarments, which contact diaper 20. In particularembodiments of the invention, backsheet 22 can include a film, such as apolyethylene film, having a thickness of from about 0.012 millimeters(0.5 mil) to about 0.051 millimeters (2.0 mils). For example, thebacksheet film can have a thickness of about 1.25 mil.

Alternative constructions of the backsheet may comprise a woven ornon-woven fibrous web layer which has been totally or partiallyconstructed or treated to impart the desired levels of liquidimpermeability to selected regions that are adjacent or proximate theabsorbent composite. For example, the backsheet may include agas-permeable, nonwoven fabric layer laminated to a polymer film layerwhich may or may not be gas-permeable. Other examples of fibrous,cloth-like backsheet materials can comprise a stretch thinned or stretchthermal laminate material composed of a 0.6 mil (0.015 mm) thickpolypropylene blown film and a 0.7 ounce per square yard (23.8 gsm)polypropylene spunbond material (2 denier fibers). A material of thistype forms the outercover of a HUGGIES SUPREME diaper, which iscommercially available from Kimberly-Clark Corporation. The backsheet 22typically provides the outer cover of the article. Optionally, however,the article may include a separate outer cover component member which isadditional to the backsheet.

Backsheet 22 may alternatively include a micro-porous, “breathable”material which permits gases, such as water vapor, to escape fromabsorbent composite 26 while substantially preventing liquid exudatesfrom passing through the backsheet. For example, the breathablebacksheet may be composed of a microporous polymer film or a nonwovenfabric which has been coated or otherwise modified to impart a desiredlevel of liquid impermeability. For example, a suitable microporous filmcan be a PMP-1 material, which is available from Mitsui ToatsuChemicals, Inc., a company having offices in Tokyo, Japan; or anXKO-8044 polyolefin film available from 3M Company of Minneapolis, Minn.The backsheet may also be embossed or otherwise provided with a patternor matte finish to exhibit a more aesthetically pleasing appearance.

In the various configurations of the invention, where a component suchas the backsheet 22 or the containment flaps 82 are configured to bepermeable to gas while having a resistance and limited permeability toaqueous liquid, the liquid resistant material can have a constructionwhich is capable of supporting a hydrohead of at least about 45 cm ofwater substantially without leakage therethrough. A suitable techniquefor determining the resistance of a material to liquid penetration isFederal Test Method Standard FTMS 191 Method 5514, dated Dec. 31, 1968,or a substantially equivalent procedure.

The size of the backsheet 22 is typically determined by the size ofabsorbent composite 26 and the particular diaper design selected.Backsheet 22, for example, may have a generally T-shape, a generallyT-shape or a modified hourglass shape, and may extend beyond theterminal edges of absorbent composite 26 by a selected distance, such asa distance within the range of about 1.3 centimeters to 2.5 centimeters(about 0.5 to 1.0 inch), to provide at least a portion of the side andend margins.

Topsheet 24 presents a body-facing surface which is compliant,soft-feeling, and non-irritating to the wearer's skin. Further, thetopsheet 24 can be less hydrophilic than absorbent composite 26, and issufficiently porous to be liquid permeable, permitting liquid to readilypenetrate through its thickness to reach the absorbent body composite. Asuitable topsheet layer 24 may be manufactured from a wide selection ofweb materials, such as porous foams, reticulated foams, aperturedplastic films, natural fibers (for example, wood or cotton fibers),synthetic fibers (for example, polyester or polypropylene fibers), or acombination of natural and synthetic fibers. The topsheet layer 24 istypically employed to help isolate the wearer's skin from liquids heldin absorbent composite 26.

Various woven and nonwoven fabrics can be used for topsheet 24. Forexample, the topsheet may be composed of a meltblown or spunbonded webof the desired fibers, and may also be a bonded-carded-web,hydroentangled web, needled web or the like, as well as combinationsthereof. The various fabrics can be composed of natural fibers,synthetic fibers or combinations thereof. Optionally, the topsheet mayinclude a net material or an apertured film.

For the purposes of the present description, the term “nonwoven web”means a web of fibrous material which is formed without the aid of atextile weaving or knitting process. The term “fabrics” is used to referto all of the woven, knitted and nonwoven fibrous webs, as well ascombinations thereof.

The topsheet fabrics may be composed of a substantially hydrophobicmaterial, and the hydrophobic material may optionally be treated with asurfactant or otherwise processed to impart a desired level ofwettability and hydrophilicity. In a particular embodiment of theinvention, topsheet 24 is a nonwoven, spunbond polypropylene fabriccomposed of about 2.8-3.2 denier fibers formed into a web having a basisweight of about 22 gsm and density of about 0.06 gm/cc. The fabric issurface treated with about 0.28% Triton X-102 surfactant. The surfactantcan be applied by any conventional means, such as spraying, printing,brush coating or the like.

The topsheet 24 and backsheet 22 are connected or otherwise associatedtogether in an operable manner. As used herein, the term “associated”encompasses configurations in which topsheet 24 is directly joined tobacksheet 22 by affixing topsheet 24 directly to backsheet 22, andconfigurations wherein topsheet 24 is indirectly joined to backsheet 22by affixing topsheet 24 to intermediate members which in turn areaffixed to backsheet 22. Topsheet 24 and backsheet 22 can, for example,be affixed directly to each other in the diaper periphery by attachmentmeans (not shown) such as adhesive bonds, sonic bonds, thermal bonds,pinning, stitching or any other attachment means known in the art, aswell as combinations thereof. For example, a uniform continuous layer ofadhesive, a patterned layer of adhesive, a sprayed pattern of adhesiveor an array of separate lines, swirls or spots of construction adhesivemay be used to affix topsheet 24 to backsheet 22. It should be readilyappreciated that the above-described attachment means may also beemployed to suitably interconnect, assemble and/or affix together thevarious other component parts of the articles which are describedherein.

The representatively shown article has an absorbent system whichincludes the surge layer 84 and the retention portion for holding andstoring absorbed liquids and other waste materials. In particularaspects of the invention, the retention or storage portion is providedby the shown absorbent core structure 26 which is composed of multiplelayers of selected fibers and high-absorbency particles. The shownconfiguration of the absorbent composite is positioned and sandwichedbetween topsheet 24 and backsheet 22 to form the diaper 20. Theabsorbent composite has a construction which is generally compressible,conformable, non-irritating to the wearer's skin, and capable ofabsorbing and retaining body exudates.

In the various configurations of the invention, many suitable types ofwettable, hydrophilic fibrous material can be used to form any of thevarious component parts of the absorbent article. Examples of suitablefibers include naturally occurring organic fibers composed ofintrinsically wettable material, such as cellulosic fibers; syntheticfibers composed of cellulose or cellulose derivatives, such as rayonfibers; inorganic fibers composed of an inherently wettable material,such as glass fibers; synthetic fibers made from inherently wettablethermoplastic polymers, such as particular polyester or polyamidefibers; and synthetic fibers composed of a nonwettable thermoplasticpolymer, such as polypropylene fibers. The fibers may be hydrophilized,for example, by treatment with silica, treatment with a material whichhas a suitable hydrophilic moiety and is not readily removable from thefiber, or by sheathing the nonwettable, hydrophobic fiber with ahydrophilic polymer during or after the formation of the fiber. For thepurposes of the present invention, it is contemplated that selectedblends of the various types of fibers mentioned above may also beemployed.

As used in the present description, the term “hydrophilic” describesfibers or the surfaces of fibers which are wetted by the aqueous liquidsin contact with the fibers. The degree of wetting of the materials can,in turn, be described in terms of the contact angles and the surfacetensions of the liquids and materials involved. Equipment and techniquessuitable for measuring the wettability of particular fiber materials orblends of fiber materials can be provided by a Cahn SFA-222 SurfaceForce Analyzer System, or a substantially equivalent system. Whenmeasured with such system, fibers having contact angles less than 90°are designated “wettable”, while fibers having contact angles equal toor greater than 90° are designated “nonwettable”.

In particular, the absorbent core structure 30 can comprise one or morematrices of fibers, such as a web of natural fibers, synthetic fibersand the like, as well as combinations thereof. Desirably the fibers arehydrophilic, either naturally or through the effects of a conventionalhydrophilic treatment. Particular arrangements can include a fibrousmatrix composed of cellulosic woodpulp fluff. It should be readilyappreciated that each of the primary layer regions 48 and 50 can includethe same types of fibrous matrices or may include different types offibrous matrices.

In particular aspects of the invention, the fibers in one or more of theprimary layers 48 and 50 can be mixed or otherwise incorporated withparticles of high-absorbency material. The fibers in the selected layeror layers are arranged in an absorbent matrix, and desirably, each ofthe layers 48 and 50 can include fibers combined with particles of thehigh-absorbency material. In particular arrangements, for example, theappointed layer of the absorbent core 30 may comprise a mixture ofsuperabsorbent hydrogel-forming particles and natural fibers, syntheticpolymer meltblown fibers, a fibrous coform material comprising a blendof natural fibers and/or synthetic polymer fibers. The superabsorbentparticles may be substantially homogeneously mixed with the hydrophilicfibers, or may be nonuniformly mixed. For example, the concentrations ofsuperabsorbent particles may be arranged in a non-step-wise gradientthrough a substantial portion of the thickness (z-direction) of eachlayer of the absorbent structure, with lower concentrations toward thebodyside of the absorbent composite and relatively higher concentrationstoward the outerside of the absorbent structure. Suitable z-gradientconfigurations are described in U.S. Pat. No. 4,699,823 issued Oct. 13,1987 to Kellenberger et al., the entire disclosure of which isincorporated herein by reference in a manner that is consistent (not inconflict) with the present description. Alternatively, theconcentrations of superabsorbent particles may be arranged in anon-step-wise gradient, through a substantial portion of the thickness(z-direction) of each layer of the absorbent structure, with higherconcentrations toward the bodyside of the absorbent composite andrelatively lower concentrations toward the outerside of the absorbentstructure. The superabsorbent particles may also be arranged in agenerally discrete layer within the matrix of hydrophilic fibers. Inaddition, two or more different types of superabsorbent may beselectively positioned at different locations within or along the fibermatrix.

The high-absorbency material may comprise absorbent gelling materials,such as superabsorbents. Absorbent gelling materials can be natural,synthetic and modified natural polymers and materials. In addition, theabsorbent gelling materials can be inorganic materials, such as silicagels, or organic compounds such as cross-linked polymers. The term“cross-linked” refers to any means for effectively rendering normallywater-soluble materials substantially water insoluble but swellable.Such means can include, for example, physical entanglement, crystallinedomains, covalent bonds, ionic complexes and associations, hydrophilicassociations, such as hydrogen bonding, and hydrophobic associations orVan der Waals forces.

Examples of synthetic absorbent gelling material polymers include thealkali metal and ammonium salts of poly(acrylic acid) and poly(methacrylic acid), poly(acrylamides), poly(vinyl ethers), maleicanhydride copolymers with vinyl ethers and alpha-olefins, poly(vinylpyrrolidone), poly(vinylmorpholinone), poly(vinyl alcohol), and mixturesand copolymers thereof. Further polymers suitable for use in theabsorbent composite include natural and modified natural polymers, suchas hydrolyzed acrylonitrile-grafted starch, acrylic acid grafted starch,methyl cellulose, chitosan, carboxymethyl cellulose, hydroxypropylcellulose, and the natural gums, such as alginates, xanthan gum, locustbean gum and the like. Mixtures of natural and wholly or partiallysynthetic absorbent polymers can also be useful in the presentinvention. Other suitable absorbent gelling materials are disclosed byAssarsson et al. in U.S. Pat. No. 3,901,236 issued Aug. 26, 1975.Processes for preparing synthetic absorbent gelling polymers aredisclosed in U.S. Pat. No. 4,076,663 issued Feb. 28, 1978 to Masuda etal. and U.S. Pat. No. 4,286,082 issued Aug. 25, 1981 to Tsubakimoto etal.

Synthetic absorbent gelling materials typically are xerogels which formhydrogels when wetted. The term “hydrogel”, however, has commonly beenused to also refer to both the wetted and unwetted forms of thematerial.

As mentioned previously, the high-absorbency material used in theabsorbent core 30 can be a superabsorbent gelling material, and thesuperabsorbent can be generally in the form of discrete particles. Theparticles can be of any desired shape, for example, spiral orsemi-spiral, cubic, rod-like, polyhedral, etc. Shapes having a largegreatest dimension/smallest dimension ratio, like needles, flakes, andfibers, are also contemplated for use herein. Optionally, conglomeratesof particles of absorbent gelling material may also be used in absorbentcomposite 26. Desired for use are particles having an average size offrom about 5 microns to about 1 millimeter. “Particle size” as usedherein means the weighted average of the smallest dimension of theindividual particles.

In particular aspects of the invention, the absorbent gelling materialparticles can have a Modified Absorbency Under Load (MAUL) of at leastabout 20 grams of absorbed liquid per gram of absorbent material (g/g).Desirably, the superabsorbent material can have a MAUL of at least about24 g/g, and more desirably can have a MAUL of at least about 27 g/g. Infurther aspects, the absorbent material can exhibit a MAUL of up toabout 30 g/g or more. The MAUL value can be measured using the MAUL testmethod described in the Testing Procedures section of the presentdescription.

The hydrophilic fibers and high-absorbency particles in the totalcomposite core 30 can be configured to form an average composite basisweight which is within the range of about 400-900 gsm (g/m²). In certainaspects of the invention, the average composite basis weight is withinthe range of about 500-800 gsm, and preferably is within the range ofabout 550-750 gsm to provide desired performance. In particular aspectsof the invention, the high-absorbency material can include asuperabsorbent nonwoven material. The superabsorbent nonwoven is anonwoven material which is composed of superabsorbent fibers alone or iscomposed of a composite of superabsorbent fibers and other materials.The superabsorbent nonwoven material has a high ultimate liquid storagecapacity when immersed in a liquid, particularly a 0.9% saline solution,with a liquid holding capacity of at least about 10 grams of absorbedliquid per gram of absorbent material (g/g). Alternatively, the liquidholding capacity is at least about 20 g/g, and optionally is at leastabout 30 g/g to provide improved performance characteristics. Thesuperabsorbent nonwoven is selectively configured to promote liquidintake, liquid storage, liquid distribution, or some combination ofthese functions. In particular, the superabsorbent nonwoven can beengineered to perform a specific function or set of functions when thesuperabsorbent nonwoven is incorporated as a layer or component in aproduct having a multilayered absorbent structure.

To limit any undesired movement of the high-absorbency material, thearticle can include an absorbent composite 26 having an over-wrap, suchas wrap sheet 28, which is placed immediately adjacent and around theentire absorbent core 30, around an individual layer region of the core,or around one or more selected components of the absorbent composite, asdesired. In addition, the wrap sheet may be bonded to the absorbentcomposite structure and to the various other components of the article.The wrap sheet is preferably a layer of absorbent material which coversthe major bodyside and outerside surfaces of the absorbent composite,and preferably encloses substantially all of the peripheral edges of theabsorbent composite to form a substantially complete envelopethereabout. Alternatively, the wrap sheet can provide an absorbentwrapping which covers the major bodyside and outerside surfaces of theabsorbent composite, and encloses substantially only the lateral sideedges of the absorbent composite. Accordingly, both the linear and theinwardly curved portions of the lateral side edges of the wrap sheetwould be closed about the absorbent composite. In such an arrangement,however, the end edges of the wrap sheet may not be completely closedaround the end edges of the absorbent composite at the waistband regionsof the article.

For example, the complete wrap sheet 28, or at least the bodyside layerof the wrap sheet, may comprise a meltblown web composed of meltblownfibers, such as meltblown polypropylene fibers. Another example ofabsorbent wrap 28 may comprise a low porosity cellulosic web, such as atissue composed of an approximately 50/50 blend of hardwood/softwoodfibers.

The absorbent wrap 28 may comprise a multi-element wrapsheet whichincludes a separate bodyside wrap layer and a separate outerside wraplayer, each of which extends past all or some of the peripheral edges ofthe absorbent core 30. Such a configuration of the wrap sheet can, forexample, facilitate the formation of a substantially complete sealingand closure around the peripheral edges of the absorbent core 30. In theback waistband portion of the illustrated diaper, the absorbent wrap mayalso be configured to extend an increased distance away from theperiphery of the absorbent core to add opacity and strength to the backside-sections of the diaper. In the illustrated embodiment, the bodysideand outerside layers of absorbent wrap 28 can extend at least about ½inch beyond the peripheral edges of the absorbent core to provide anoutwardly protruding, flange-type bonding area over which the peripheryof the bodyside portion of the absorbent wrap may be completely orpartially connected to the periphery of the outerside portion of theabsorbent wrap.

The bodyside and outerside layers of wrap sheet 28 may be composed ofsubstantially the same material, or may be composed of differentmaterials. For example, the outerside layer of the wrap sheet may becomposed of a relatively lower basis weight material having a relativelyhigh porosity, such as a wet strength cellulosic tissue composed ofsoftwood pulp. The bodyside layer of the wrap sheet may comprise one ofthe previously described wrap sheet materials which has a relatively lowporosity. The low porosity bodyside layer can better prevent themigration of superabsorbent particles onto the wearer's skin, and thehigh porosity, lower basis weight outerside layer can help reduce costs.

With reference to FIGS. 7, 8 and 9, another absorbent core of theinvention can include a component having particles of superabsorbentmaterial 102 operatively held between layers of liquid permeablematerial 100, such as layers of tissue, open cell foam, porous films,woven fabric, nonwoven fabric or the like, as well as combinationsthereof. In particular aspects of the invention, the bottom layer 50 maybe composed of a laminate having superabsorbent particles sandwiched orotherwise held between layers of carrier tissue held withwater-sensitive attachments. Examples of such configurations aredescribed in U.S. Pat. No. 5,593,399 issued Jan. 14, 1997 to R. Tanzeret al. and entitled ABSORBENT ARTICLE WHICH INCLUDES SUPERABSORBENTMATERIAL LOCATED IN DISCRETE, ELONGATE POCKETS PLACED IN SELECTEDPATTERNS (attorney docket No. 10,902.1), the entire disclosure of whichis incorporated by reference in a manner that is consistent herewith.

With reference again to FIGS. 1 and 2, the diaper 20 can also include asurge management layer 84 which helps to decelerate and diffuse surgesof liquid that may be directed into the retention and storage portion ofthe absorbent article. The surge layer 84 can, for example, be locatedon an inwardly facing body side surface of topsheet layer 24. In therepresentatively shown configuration, surge layer 84 is located adjacentto an outer side surface of the topsheet layer. Accordingly, the surgelayer is interposed between the topsheet 24 and absorbent core 30.Examples of suitable surge management layers 84 are described in U.S.patent application Ser. No. 206,986 of C. Ellis and D. Bishop, entitledFIBROUS NONWOVEN WEB SURGE LAYER FOR PERSONAL CARE ABSORBENT ARTICLESAND THE LIKE, filed Mar. 4, 1994 (attorney docket No. 11,256) whichissued as U.S. Pat. No. 5,486,166; and U.S. patent application Ser. No.206,069 of C. Ellis and R. Everett, entitled IMPROVED SURGE MANAGEMENTFIBROUS NONWOVEN WEB FOR PERSONAL CARE ABSORBENT ARTICLES AND THE LIKE,filed Mar. 4, 1994 (attorney docket No. 11,387) which issued as U.S.Pat. No. 5,490,846; the entire disclosures of which are herebyincorporated by reference in a manner that is consistent herewith.

With reference to FIGS. 1 and 2, particular aspects of the invention caninclude an absorbent composite which includes a selected plurality oftwo or more primary, layer-region components. The configuration of theillustrated multilayer absorbent core 30, for example, includes a firstlayer-region 48 and at least a second layer-region 50.

The representatively shown first layer region 48 provides a relativelyupper layer region which is positioned on the bodyside region of theabsorbent core 30 and is relatively more closely adjacent to thetopsheet layer 24. The illustrated second layer region 50 provides arelatively lower layer region which is positioned on the outward-sideregion of the absorbent core and is relatively more closely adjacent tothe backsheet layer 22.

In a desired aspect of the invention, the components in the variouslayer regions, such as the layer regions 48 and/or 50, can include ablend or other matrix of high bulk fibers. High bulk fibers are thosewhich impart improved bulk retention and/or recovery from deformation.The high bulk fibers can particularly provide wet bulk retention, and/orwet recovery from deformation when the fibers are incorporated intomaterials which become wetted. Examples of suitable high bulk fibersinclude synthetic, thermoplastic fibers, synthetic fibers composed ofnatural polymers such as cellulose, and natural fibers, as well ascombinations thereof. The resiliency of fibers composed of naturalpolymers can be enhanced by chemical crosslinking and/or by impartingkink and/or curl to the fiber.

The high bulk fibrous materials are able to exhibit a lower density inboth their wet state and dry state, and thereby increase thepermeability and thickness, thus increasing the Flow Conductance Value.For example, high bulk wood pulp fibers can be achieved through varioustechniques, such as through chemical and/or mechanical modifications ofthe pulp fibers. Examples of suitable high bulk fibers includemercerized fibers, crosslinked cellulose fluff pulp fibers and the like,as well as combinations thereof.

In another aspect of the invention, the components in the various layerregions, such as the layer regions 48 and/or 50, can be composed of ablend or other matrix of the high bulk fibers, and a controlled-ratesuperabsorbent. The controlled-rate superabsorbent is a material, suchas a superabsorbent polymer material, which demonstrates a modifiedabsorbency-under-load (MAUL) value of at least a minimum of about 20g/g.

In a further aspect of the invention, the desired controlled-ratesuperabsorbent can exhibit a particular absorbency rate, Tau (τ) value,such as a Tau value which is at least a minimum value of about 0.4 min.Desirably, the superabsorbent Tau value is at least about 1 min, and canbe at least about 2 min to provide improved performance. In still otheraspects the Tau value can be up to about 40 minutes or more. In otheraspects, the absorbent core, particularly the different layer regions ofthe absorbent core, can advantageously incorporate a selectedcombination of superabsorbent materials wherein at least a selected pairof different superabsorbent materials are configured to provide aTau-value-ratio which is equal to or greater than about 2:1. TheTau-value-ratio can optionally be up to about 5:1, or more, to providefurther benefits. Desirably, the superabsorbent material having therelatively greater Tau value is positioned relatively closer to thebodyside surface of the absorbent core. A suitable technique fordetermining the Tau value of each superabsorbent is described in theFlooded Absorbency Under Zero Load procedure set forth in the presentdescription.

A particular controlled-rate superabsorbent can be a superabsorbentwherein the individual superabsorbent particles are treated with ahydrophobic coating to provide a selected delay in the absorption ofaqueous liquids into the particles. For example, the superabsorbent maybe a coated particulate superabsorbent. The particles have absorbentcenters composed of a partial sodium salt of a cross-linked polyproponicacid (prepared by the process described in U.S. Pat. No. 5,629,377), andthe particle centers are covered with a hydrophobic silicone elastomercoating. A representative controlled-rate superabsorbent of this type isavailable from DOW Chemical Company, a business having offices inMidland, Mich., U.S.A.

An alternative controlled-rate superabsorbent can be configured withrelatively large particle sizes to provide particles having a low,surface area to volume ratio which thereby produces the desiredabsorbency rate. The controlled-rate superabsorbent particles can alsohave a substantially spherical or other three-dimensional shape whichoperatively generates the desired low ratio of surface-area-to-volumeand delayed absorbency rate.

In addition, the bulk chemistry of the superabsorbent polymer can bemodified to provide the desired, delayed absorbency rate. For example,the controlled-rate superabsorbent may incorporate an anionicpolyelectrolyte which is reversibly crosslinked with a polyvalent metalcation. A water soluble complexing agent may be configured to reversethe crosslinking.

Alternative controlled-rate superabsorbents can be encased by a coatingor other treatment which operatively slows the diffusion of liquid intothe superabsorbent particles, or repels liquid in a manner whichprovides the desired delayed absorbency rate. The coatings or treatmentsmay be elastic or inelastic, and the coating or treatment may behydrophobic or hydrophilic. The coatings may erode, dissolve, or crackin a controlled fashion to provide the desired absorbencycharacteristics. Optionally, the absorbency rate may be limited and/orcontrolled by modifying the neutralization rate of the selectedsuperabsorbent material, or by modifying or otherwise controlling thechemical mechanism employed to produce the neutralization of theselected superabsorbent.

Additional aspects of determining the absorbency under load (AUL) of asuperabsorbent are described in U.S. Pat. No. 5,550,189 issued Aug. 26,1996 to J. Qin et al. and entitled MODIFIED POLYSACCHARIDES HAVINGIMPROVED ABSORBENT PROPERTIES AND PROCESS FOR THE PREPARATION THEREOF;and in U.S. patent application Ser. No. 621,390 of M. Melius et al.filed Mar. 25, 1996 and entitled ABSORBENT COMPOSITE (attorney docketNo. 10,838.2), which corresponds to U.S. Pat. No. 5,601,542 issued Feb.11, 1997. The entire disclosures of these documents are herebyincorporated by reference in a manner that is consistent herewith.

With reference to FIGS. 2 and 2A, the representatively shown first layerregion 48 can include a controlled-rate superabsorbent, and a high bulkwood pulp fiber or other woven or nonwoven fibrous material with poresize distributions which allow for a rapid uptake of liquid whilemaintaining the liquid within the structure until it can be absorbed bythe relatively outward layer region or layer regions of the absorbent.The components in the first layer region portion 48 can be positioned tosubstantially cover the appointed target area 52 of the product, thearea where liquids, such as urine, are introduced into the absorbentstructure. Accordingly, the first layer region 48 can operatively be anappointed intake layer region of the absorbent core. The shape of thelayer region 48 can be rectangular, non-rectangular or irregular inshape, but desirably will not be larger than the underlying layerregion, such as the second layer region 50. In desired aspects of theinvention, the first layer region will be smaller than the underlying,second layer region. For example, a substantial entirety of the firstprimary layer region may be contained within a zone which begins at alaterally extending line positioned about 7% of the core length inboardfrom said front-most edge of the absorbent core and extends to alaterally extending line positioned about 62% of the core length inboardfrom said front-most edge of the absorbent core. In addition, thelongitudinally extending side edges of the first primary layer regionmay be substantially coterminous with the corresponding side edges ofthe second primary layer region.

Further examples of alternative absorbent configurations arerepresentatively shown in FIGS. 3 through 6. In particular aspects ofthe invention, the first layer region 48 may include a compositestructure having a plurality of component sub-layer portions.

FIGS. 3 and 3A representatively show a top view of an absorbent corestructure having a first, top layer region 48 which extends over amedial portion of the total area of the absorbent core 30, and a second,bottom layer region 50 which extends over substantially the entire areaof the absorbent core. The second layer region 50 has a non-uniform,zoned basis weight distribution with a relatively greater basis weightat its longitudinally opposed end portions to provide a longitudinal,reverse zoning of the lower, second layer region, particularly in thetarget area. The selected medial portion of the second layer region 50can also have a basis weight which is lower than that of the adjacent,overlying first layer region 48, to provide a reversed zoned thicknessin the target area. At least in the crotch region of the absorbent core30, the lateral side edges of the top layer region 48 are substantiallycoterminous with the side edges of the second layer region 50. Each ofthe longitudinal end edges of the first layer region 48 are spacedinboard from the corresponding end edges of the second layer region 50.

FIGS. 4 and 4A representatively show an absorbent core structure havinga top layer region 48 which covers an entire front or first portion ofthe bottom layer region 50, but covers less than the entire back orsecond portion of the bottom layer region. The lateral side edges and atleast one longitudinal end edge of the first layer 48 are substantiallycoterminous with the lateral side edges and at least one longitudinalend edge of the second layer region 50. In the shown configuration, atleast one longitudinal end edge of the first layer region 48 is spacedinboard from a corresponding end edge of the second layer region 50.

FIGS. 5 and 5A representatively show an absorbent core structure havinga top layer region which entirely covers a bottom layer region. Whilethe shown configuration has a first layer region 48 and a second layerregion 50 with substantially the same thicknesses and basis weights, thefirst and second layer regions may alternatively have differentthicknesses and basis weights, as well as other differences instructure.

FIG. 6 representatively shows a top view of another absorbent core witha top layer region which has both a lesser, narrower lateral dimensionand a lesser, shorter longitudinal dimension than the bottom layerregion. In the shown configuration, for example, substantially theentire outer edge perimeter of the first layer region 48 is spacedinboard from substantially the entire outer edge perimeter of the secondlayer region 50.

In the various configurations of the invention, the controlled-ratesuperabsorbent can be configured to help regulate the rate of liquidstorage in the various layer regions of the absorbent system. Thecontrolled-rate superabsorbent can provide a rate control of liquidstorage in an absorbent solely as a result of the presence of thecontrolled-rate superabsorbent material (SAM), or in combination of thesuperabsorbent with other materials to provide a controlled-ratesuperabsorbent composite. A controlled-rate superabsorbent or asuperabsorbent composite material employing the controlled-ratesuperabsorbent can be used as an absorbent layer region in a multilayerregion absorbent, particularly when the controlled-rate superabsorbentor the controlled-rate superabsorbent composite material is selectivelyconfigured to promote preferential saturation of one or more of theother layer regions in the multilayer absorbent core during in-useconditions. By using a combination of the high bulk fibers and thecontrolled-rate superabsorbent, the saturation in the first layer region48 can be maintained at a saturation level which is lower than that ofthe other absorbent layer regions, resulting in higher void volume andpermeability in the first layer region 48, and providing desired levelsof the Flow Conductance Value.

The composite composed of high bulk fiber, particularly pulp fiber, andsuperabsorbent may also be modified by introducing a stabilizing agentto the composite material. The structure stabilization can be employedto maintain or minimize changes to the structure of a particularmaterial or to the structure of the composite of materials when exposedto external or internal forces. The structure stabilization mechanismmay benefit any layer region in the multiple layer-region absorbent byhelping to maintain the layer region's structure when it is exposed toforces applied during in-use conditions for the products whichincorporate the multiple layer absorbent core. This will help the layerregion maintain its intended function, whether that be liquid intake(void volume generation), liquid storage, liquid distribution, or somecombination of these three functions. Various types of suitable materialtechnologies may be employed to stabilize absorbent structures. Forexample, the stabilization may occur either in the form of chemicalstabilization, such as with Kymene or another cross-linking agent, or bythe introduction of thermoplastic binder fibers or the like.

In the various aspects of the invention, the upper layer region 48 maybe composed of a fibrous material based on a woven or nonwoventechnology. As in the previous aspects of the invention, these materialswill be configured to provide maximum void volume and permeability whilemaintaining enough capillary tension to control the movement of theliquid and not allow leakage to occur. For example, the absorbent coresof the present invention could incorporate nonwoven materials asfunctional components for the top layer region 48. Bonded carded websare examples of particular fibrous materials that could be configured toprovide an adequate balance of permeability and capillarity. Through theselection of staple fiber options, one can create a composite structurethat will preferentially saturate the bottom absorbent layer 50. Thiscan be done either through physical structuring of the top layer,controlled surface chemistry or both. The porosity of fibrous structurescan be determined by the specific fibers and fiber sizes selected. Fiberselection can also impact the capillarity of the material.

Suitable carded structures have been produced from a variety of fibertypes and from an assortment of fiber sizes. Fibers can be produced fromboth synthetic and naturally occurring materials. Desirably, the fibersfor the first layer 48 would be very wettable, and natural cellulosicmaterials such as rayon or cotton may be employed. Synthetic fibers suchas polyester and polyamide offer limited wettability which could beenhanced with hydrophilic finishes or treatments. While fiber diametersof a fairly wide range occur in carded nonwovens the desired structurewould contain fibers with equivalent diameters less than 25 microns. Acarded material for the first layer 48 could be produced in a weightrange from about 50 to 200 grams per square meter (gsm) at a density ofabout 0.03 g/cc or less. The density of the fibrous material willultimately depend upon the method used to bond or stabilize the web.

Carded webs can be stabilized through various methods. Incorporation ofthermoplastic staple fibers is used in some cases so that the structuremight be bonded using heat and pressure. Proper application of heat andpressure in thermal bonding can result in a structure that is stabilizedwith very specific permeability and capillarity. Carded structures canalso be stabilized using chemical resins or adhesives. Again, selectionof the specific resin or adhesive, add-on amounts and curing willfacilitate control of the final web properties which impact permeabilityand capillarity. Wettability can be impacted by the choice of chemicalresin system for bonding. Carded structures can be mechanicallystabilized using water, needling, air or other means to entangle fibers.Again, these processes can be controlled in such a way that physicalattributes of the material are as desired.

Particular aspects of the invention can incorporate a spunbonded fabricwith properties similar to that described above. Other aspects of theinvention may also include a selected zoning of the fiber size, basisweight, or other features of the material to provide desired performanceattributes. In addition to carded fibrous webs and meltspun fibrouswebs, airlaid fibrous materials may also be used.

The component materials in the first layer region 48 can be in theamounts, basis weights, densities, etc. that are described below.Typical basis weights of the region of the absorbent core structurewhich is positioned in a front half-portion of the article can be fromabout 750 gsm to about 950 gsm. The first layer region, as describedabove, can provide anywhere from about 25% to about 75% of the overall,composite basis weight in those areas where the first layer is present.This ratio is highly dependent on the materials being used and theirrelative efficiencies. The materials in which superabsorbent materialsare used in combination with fluff and/or some staple fibers usuallywill have an initial density of 0.1 g/cc to 0.3 g/cc. The materialswhich are synthetic based, carded webs and melt-spun webs, willtypically have a density of about 0.015 g/cc to 0.3 g/cc, and willdesirably have a density of about 0.2 g/cc. Webs of synthetic fiberswill have fiber sizes typically less than 3 denier and preferentiallyfrom 1-2 denier and will be treated to exhibit a low contact angle withwater through several wettings. The treatment desirably does not reducethe surface tension of the liquid which passes through the fibrous web.

Other nonwoven structures may also be suitable for use as the upperlayer region 48 in absorbent system of the invention. A proper balanceof the capacity and capillarity of the lower layer region can ensurepreferential saturation of the lower layer region over multiple insults.One can envision using a different lower layer region which has betterdistribution capability. This would aid in the desorption of thenonwoven upper layer region and should improve performance after thesecond insult.

Desired aspects of the invention can have a Liquid Wicking Value whichis greater than a value of about 36%. Other aspects of the invention canhave a Liquid Wicking Value greater than about 16%, and a FlowConductance Value which is greater than a value of about 7×10⁻⁶ cm³. Instill other aspects, the invention can have a CombinedConductance-Wicking Value (C) which is at least about 14*10⁻⁶ cm³.

The desired combinations of Flow Conductance and Wicking Values canprovide an advantageous balance of liquid handling characteristics. Inparticular, the combinations can provide a desired balance of a rapidintake of the liquid along with a rapid transport of the absorbed liquidaway from the intake-target area to more remote areas of the absorbentstructure. Conventional structures have not provided the desiredcombination of properties. Accordingly, structures which have provided adesired rapid intake have not provided a sufficiently rapid transport ofthe absorbed liquid away from the intake area, and structures which haveprovided a desired rapid transport of the absorbed liquid away from theintake area have not provided a sufficiently rapid intake of the liquid.As a result, the can be a premature, excessive saturation of theabsorbent target area, or an excessive pooling of liquid against thewearer's skin.

In particular aspects of the invention, the first layer region 48 can bea top, bodyside layer which can typically extend over a longitudinallymedial section of the overall core area, but may optionally extend overthe entire core area, if desired. The top layer typically is the layerwhich is optimized for intake performance and may or may not providedesired levels of liquid wicking or distribution performance. The firstlayer region typically can have a minimum basis weight of not less thanabout 100 gsm, and desirably can have a basis weight of not less thanabout 200 gsm. In further aspects, the first layer region typically canhave a maximum basis weight of not more than about 500 gsm, anddesirably has a basis weight of not more than about 450 gsm.

The first layer portion typically includes a minimum of not less thanabout 25% fibrous material by weight (wt %), and desirably includes notless than about 40% fibrous material. In other aspects, first layerportion typically can include a maximum of not more than about 80%fibrous material, and desirably can include not more than about 60%fibrous material. The fibrous material may be natural or synthetic innature. The fibrous material can have a minimum fiber size, particularlya fiber diameter, of at least about 4 microns (μm), and desirably has afiber size of at least about 10 microns. In further aspects, fibrousmaterial can have a maximum fiber size of not more about 20 microns, anddesirably has a fiber size of not more than about 15 microns. The fiberscan exhibit a water contact angle of not more than about 65 degrees.

The first layer portion can also contain a minimum of not less thanabout 20% of superabsorbent material by weight, and desirably containsnot less than about 30% superabsorbent. In additional aspects, the firstlayer portion can include a maximum of not more than about 75%superabsorbent material, and desirably can include not more than about50% superabsorbent. The superabsorbent material can have a minimum, dryparticle size of not less than about 140 microns, and desirably has adry particle size of not less than about 300 microns. In other aspectsthe superabsorbent material can have a maximum, dry particle size of notmore than about 1000 microns, and desirably can have a dry particle sizeof not more than about 700 microns. The superabsorbent material can alsohave a MAUL value of not less than about 20 g/g, and desirably can havea MAUL value of not less than about 25 g/g. Additionally, the MAUL valuecan be up to about 30 g/g, or more to provide improved benefits. Infurther aspects, the superabsorbent material can have a Tau value of atleast about 0.8 minutes, and can have a Tau value of up to about 40minutes.

The first layer region 48 can typically have a minimum average densityof at least about 0.03 g/cc, and desirably has a density of at leastabout 0.05 g/cc. In other aspects, the first layer region can have amaximum average density of not more than about 0.4 g/cc, and desirablycan have a density of not more than about 0.2 g/cc. The first layerregion includes any tissue layers which are used to hold together thematerials positioned in the first layer region or which act as a carriermechanism. For example, several layers of tissue may be employed to holdsuperabsorbent material which is laminated between the tissue layers.

The various configurations of the invention can include any operativeintake material in the selected layers of the absorbent structure.Examples of suitable intake materials can include the materialsdescribed in U.S. patent application Ser. No. 754,414 entitledMULTIFUNCTIONAL ABSORBENT MATERIAL AND PRODUCTS MADE THEREFROM, by R.Anderson et al., and filed Nov. 22, 1996 (attorney docket No. 12,442),now U.S. Pat. No. 5,843,063 issued Dec. 1, 1998; and in U.S. ProvisionalPatent Application Ser. No. 068,534 (abandoned) entitled PULP ANDSUPERABSORBENT COMPOSITE FOR IMPROVED INTAKE PERFORMANCE, by L. H.Sawyer et al., and filed Dec. 23, 1997 (attorney docket No. 13,041),which corresponds to PCT publication WO 99/32165 dated Jul. 1, 1999. Theentire disclosures of these documents are incorporated herein byreference in a manner that is consistent herewith.

With reference to FIGS. 2 and 2A, the second layer region portion 50 caninclude a mass or matrix of hydrophilic fibers, such as wood pulpfibers, and a selected quantity of superabsorbent gelling material, suchas Coosa 1654 wood pulp and Stockhausen Favor 880 superabsorbent. Thesematerials will typically be blended or otherwise combined such thatabout 20-80 wt % of the composite is composed of superabsorbentparticles. Modifications of this material may also be made to provideimproved product performance. These modifications can include the use ofmodified pulp fibers to generate improvements in the distribution ofliquid, or the use of a stabilization technique to control the structureand generate improved wicking performance. Potential methods ofstabilization include, but are not limited to, the use of a bindermaterial, such as Kymene or some other cross-linking agent, or theintroduction of heat activated binder fibers. Structure stabilization isa technology that is used to maintain the structure or minimize changesto the structure of a material or a composite of materials when thematerials are exposed to external or internal forces. Varioustechniques, such as the incorporation of thermoplastic binder fibers,chemical cross-linking agents (such as Kymene), and the like, as well ascombinations thereof, may be employed to stabilize the absorbentstructures.

Any material which is operatively configured with the ability to provideimproved distribution of liquid away from the target area can providethe desired functional results. These materials can be composed of alaminate which includes superabsorbent particles and at least onefibrous web which is particularly configured to exhibit an improvedwicking flux performance. Suitable arrangements of the second layerregion 50 can include, but are not limited to, laminations ofparticulate or fibrous superabsorbent webs with cellulosic tissuematerials, or any other stabilized, fibrous web. Other suitable fibrouswebs may include wet laid tissue, airlaid materials incorporating staplesynthetic and natural fibers, or treated meltblown webs, as well as thetypes of fibrous webs employed to construct the first layer region 48.Another class of materials which can be used to provide improvedfunctionality are laminates of superabsorbent particles or fibrous websand wettable, open cell foams.

The second layer region 50 can be positioned in various suitableconfigurations. For example, the second layer region can be in the formof a separately provided absorbent pad which is positioned immediatelyadjacent to the first layer region 48. The second layer region 50 isdesirably in a substantially direct contact with the first layer region48, but may alternatively be positioned spaced from the upper layerregion with one or more layer regions of selected material interposedbetween the first layer region 48 and the second layer region 50. Inparticular aspects of the invention, the second layer region 50 isconfigured to allow for a maximum utilization of the absorbent to theincoming liquid while also maintaining product attributes pleasing tothe consumer.

In further aspects, the second primary layer region can have alongitudinal extent which is greater than a longitudinal extent of saidfirst primary layer region. Additionally, the second primary layerregion can have a lateral extent which is substantially coterminous withsaid first primary layer region. Alternative configurations can includea second primary layer region which has a lateral extent which is lessthan a lateral extent of said first primary layer region. For example,the lateral extent of at least a portion of the second primary layerregion can be not less than about 30% of the lateral extent of acorrespondingly adjacent portion of the first primary layer region.Other configurations can include a second primary layer region which hasa lateral extent which is greater than a lateral extent of the firstprimary layer region. For example, the lateral extent of at least aportion of the first primary layer region can be not less than about 30%of the lateral extent of a correspondingly adjacent portion of thesecond primary layer region. The component materials in the second layerregion 50 can be provided in various operative amounts, basis weights,densities, etc. For example, the second primary layer region may have asubstantially uniform basis weight. Additionally, the second layerregion 50 can constitute about 25%-100% of the overall, composite basisweight of the absorbent core structure at any one location, and maytypically have a density in the range of about 0.1 g/cc to 0.3 g/cc. Instill other aspects, the second layer region portion 50 may include aplurality of two or more component sub-layer regions, wherein each ofthe component sub-layer regions has a selected combination of physicaland functional characteristics.

In particular aspects of the invention, at least one of the layerregions of the absorbent core 30 is a distributing layer which canprovide a Liquid Wicking Potential value of not less than about 16%. Inaddition, the distributing layer has a perimeter boundary and area whichextend beyond and past the appointed target region 52 of the absorbentcomposite.

The distributing layer can advantageously provide particular importantfunctions. A first function includes the retention and movement ofliquid away from the target area, and a second function is to provideenough short term (during liquid insult) superabsorbent capacity to makeup for the shortfall in void volume associated with thin productexecutions. Structural elements of this layer region include the SAPcontent, the component basis weights, and the component densities.

The second layer region 50 can provide a bottom layer, and can typicallyextend over the entire area of the of the overall absorbent core 30. Thesecond layer region 50 is typically designed to provide the bulk of thedistribution or wicking ability of the absorbent core, and thereforewill typically extend beyond and past the terminal edges of the areacovered by the first layer region 48. The second layer region typicallycan have a basis weight of not less than about 300 gsm, and desirablycan have a basis weight of not less than about 350 gsm. In furtheraspects, the second layer region typically can have a basis weight ofnot more than about 700 gsm, and desirably has a basis weight of notmore than about 450 gsm.

The second layer portion typically includes not less than about 50%fibrous material by weight, and desirably includes not less than about60% fibrous material. In other aspects, second layer portion typicallycan include not more than about 80% fibrous material, and desirably caninclude not more than about 75% fibrous material. The fibrous materialmay be natural or synthetic in nature. The fibrous material can have afiber size, particularly a fiber diameter, of at least about 4 microns,and desirably has a fiber size of at least about 10 microns. In furtheraspects, fibrous material can have a fiber size of not more about 20microns, and desirably has a fiber size of not more than about 15microns. In addition, the fibrous material can have a contact angle withwater of not more than about 65 degrees, and desirably has a contactangle with water of not more than about 50 degrees.

The second layer portion can also contain not less than about 20% ofsuperabsorbent material, by weight, and desirably contains not less thanabout 30% superabsorbent. In additional aspects, the second layerportion can include not more than about 50% superabsorbent material, anddesirably can include not more than about 40% superabsorbent. Thesuperabsorbent material can have a dry particle size of not less thanabout 140 microns, and desirably has a dry particle size of not lessthan about 300 microns. In other aspects the superabsorbent material canhave a dry particle size of not more than about 1000 microns, anddesirably can have a dry particle size of not more than about 700microns. The superabsorbent material can also have a MAUL value of notless than about 20 g/g, and desirably can have a MAUL value of not lessthan about 25 g/g. Additionally, the MAUL value can be up to about 30g/g, or more to provide improved benefits. In still other aspects, thesuperabsorbent material can have a Tau value of at least about 0.67minutes, and can desirably have a Tau value of at least about 2 minutes.

Advantageous configurations of the invention can include a second layerregion 50 which has a Liquid Wicking Potential value of at least about36% and contains a superabsorbent having a Tau value of not less thanabout 2 minutes. Other advantageous arrangements can include a secondlayer region which has a Liquid Wicking Potential value of at leastabout 16% and contains a superabsorbent having a Tau value of not lessthan about 0.67 minutes.

In particular aspects of the invention, the superabsorbent material inthe first layer region 48 is configured to have a Tau value which isabout twice the Tau value of the superabsorbent located in the secondlayer region 50 (Tau-value-ratio of about 2:1)., The Tau-value-ratio canalternatively be at least about 2.5:1, and optionally, can be at leastabout 3:1 to provide desired characteristics. In additional aspects, thecombination of superabsorbent materials in the first and second layerregions can be configured to provide a Tau-value-ratio of up to about10:1, and alternatively, the combination of superabsorbent materials canbe configured to provide a Tau-value-ratio of up to about 40:1, or more.

The second layer region 50 can typically have an average density of atleast about 0.1 g/cc, and desirably has a density of at least about 0.15g/cc. In other aspects, the second layer region can have an averagedensity of not more than about 0.3 g/cc, and desirably can have adensity of not more than about 0.25 g/cc. In particular aspects, theaverage density can be about 0.2 g/cc. The second layer region includesany tissue layers which are used to hold together the materialspositioned in the second layer region or which act as a carriermechanism. For example, several layers of tissue may be employed to holda layer of superabsorbent material which is laminated between the tissuelayers.

Further descriptions of the various configurations of the invention areprovided in U.S. patent application Ser. No. 09/519,381 of R. Everett etal., entitled LAYERED ABSORBENT STRUCTURE WITH A ZONED BASIS WEIGHT, andfiled Mar. 3, 2000 (attorney docket No. 13,506.2); U.S. patentapplication Ser. No. 09/518,756 of R. Everett et al., entitled LAYEREDABSORBENT STRUCTURE WITH A HETEROGENEOUS LAYER REGION, and filed Mar. 3,2000 (attorney docket No. 13,507.2); and U.S. patent application Ser.No. 09/478,686 of R. Everett et al., entitled LAYERED ABSORBENTSTRUCTURE WITH A ZONED BASIS WEIGHT AND A HETEROGENEOUS LAYER REGION,and filed Mar. 3, 2000 (attorney docket No. 13,508.2). The entiredisclosures of each of these documents are incorporated herein byreference in a manner that is consistent herewith.

With reference again to FIG. 1, the leg elastic members 34 are locatedin the lateral side margins 110 of the diaper, and are arranged to drawand hold the diaper 20 against the legs of the wearer. The elasticmembers are secured to diaper 20 in an elastically contractiblecondition so that in a normal under strain configuration, the elasticmembers effectively contract against diaper 20. The elastic members canbe secured in an elastically contractible condition in at least twoways, for example, the elastic members may be stretched and securedwhile diaper 20 is in an uncontracted condition. Alternatively, diaper20 may be contracted, for example, by pleating, and the elastic memberssecured and connected to diaper 20 while the elastic members are intheir relaxed or unstretched condition. Still other mechanisms, such asheat-shrink elastic material, may be used to gather the garment.

In the embodiment illustrated in FIG. 1, the leg elastic members 34extend essentially along the complete length of the intermediate crotchregion 42 of the diaper 20. Alternatively, elastic members 34 may extendthe entire length of the diaper 20, or any other length suitableproviding the arrangement of elastically contractible lines desired forthe particular diaper design.

Elastic members 34 may have any of a multitude of configurations. Forexample, the width of the individual elastic members 34 may be variedfrom about 0.25 millimeters (about 0.01 inch) to about 25 millimeters(about 1.0 inch) or more. The elastic members may comprise a singlestrand of elastic material, or may comprise several parallel ornon-parallel strands of elastic material, or may be applied in arectilinear or curvilinear arrangement. Where the strands arenon-parallel, two or more of the strands may intersect or otherwiseinterconnect within the elastic member. The elastic members may beaffixed to the diaper in any of several ways which are known in the art.For example, the elastic members may be ultrasonically bonded, heat andpressure sealed using a variety of bonding patterns, or adhesivelybonded to diaper 20 with sprayed or swirled patterns of an adhesive,such as a hotmelt, pressure-sensitive adhesive.

In particular embodiments of the invention, the leg elastic members 34may include a carrier sheet to which are attached a grouped set ofelastics composed of a plurality of individual elastic strands. Theelastic strands may intersect or be interconnected, or be entirelyseparated from each other. The carrier sheet may, for example, comprisea 0.002 cm thick polymer film, such as a film of unembossedpolypropylene material. The elastic strands can, for example, becomposed of LYCRA elastomer available from DuPont, a business havingoffices in Wilmington, Del. Each elastic strand is typically within therange of about 470-1500 decitex (dtx), and may be about 940-1050 dtx. Inparticular embodiments of the invention, for example, three or fourstrands can be employed for each elasticized legband.

In addition, the leg elastics 34 may be generally straight or optionallycurved. For example, the curved elastics can be inwardly bowed towardthe longitudinal centerline of the diaper. In particular arrangements,the curvature of the elastics may not be configured or positionedsymmetrically relative to the lateral centerline of the diaper. Thecurved elastics may have an inwardly bowed and outwardly bowed,reflex-type of curvature, and the length-wise center of the elastics mayoptionally be offset by a selected distance toward either the front orrear waistband of the diaper to provide desired fit and appearance. Inparticular embodiments of the invention, the innermost point (apex) ofthe set of curved elastics can be offset towards the front or rearwaistband of the diaper, and the outwardly bowed reflexed-portion can bepositioned toward the diaper front waistband.

As representatively shown, the diaper 20 can include a waist elastic 32positioned in the longitudinal margins of either or both of frontwaistband 38 and rear waistband 40. The waist elastics may be composedof any suitable elastomeric material, such as an elastomer film, anelastic foam, multiple elastic strands, an elastomeric fabric or thelike. For example, suitable elastic waist constructions are described inU.S. Pat. No. 4,916,005 to Lippert et al., the entire disclosure ofwhich is hereby incorporated by reference in a manner that is consistentherewith. The diaper 20 can also include a pair of elasticizedcontainment flaps 82 which extend generally length-wise along thelongitudinal direction 86 of the diaper. The containment flaps aretypically positioned laterally inboard from leg elastics 34, andsubstantially symmetrically placed on each side of the lengthwise,longitudinal centerline of the diaper. In the illustrated arrangements,each containment flap 82 has a substantially fixed edge portion 81 and asubstantially moveable edge portion 83, and is operably elasticized tohelp each containment flap to closely contact and conform to thecontours of the wearer's body. Examples of suitable containment flapconstructions are described in U.S. Pat. No. 4,704,116 issued Nov. 3,1987, to K. Enloe, the entire disclosure of which is hereby incorporatedby reference in a manner that is consistent herewith. The containmentflaps may be composed of a wettable or a non-wettable material, asdesired. In addition, the containment flap material may be substantiallyliquid-impermeable, may be permeable to only gas or may be permeable toboth gas and liquid. Other suitable containment flap configurations aredescribed in U.S. patent application Ser. No. 206,816 of R. Everett etal., filed Mar. 4, 1994 and entitled ABSORBENT ARTICLE HAVING ANIMPROVED SURGE MANAGEMENT (attorney docket No. 11,375) which issued asU.S. Pat. No. 5,562,650, the disclosure of which is hereby incorporatedby reference in a manner that is consistent herewith.

In optional, alternative configurations of the invention, diaper 20 mayinclude elasticized waist flaps, such as those described in U.S. Pat.No. 4,753,646 issued Jun. 28, 1988, to K. Enloe, and in U.S. patentapplication Ser. No. 560,525 of D. Laux et al. entitled AN ABSORBENTARTICLE WITH IMPROVED ELASTIC MARGINS AND CONTAINMENT SYSTEM and filedDec. 18, 1995 (attorney docket No. 11091) which corresponds to U.S. Pat.No. 5,904,675 issued May 18, 1999, the entire disclosures of which arehereby incorporated by reference in a manner that is consistentherewith. Similar to the construction of the containment flaps, thewaist flaps may be composed of a wettable or non-wettable material, asdesired. The waist flap material may be substantiallyliquid-impermeable, permeable to only gas, or permeable to both gas andliquid.

To provide a refastenable fastening system, diaper 20 can include anappointed landing zone 78 (e.g. FIG. 1A), which can provide an operabletarget area for receiving a releasable attachment of the fastener tabs44 thereon. In particular embodiments of the invention, the landing zonepatch can be positioned on the outward surface of backsheet layer 22 andis located on the front waistband portion 38 of the diaper. Thefastening mechanism between the landing zone and the fastener tabs 44may be adhesive, cohesive, mechanical or combinations thereof. Aconfiguration which employs a releasable, interengaging mechanicalfastening system can, for example, locate a first portion of themechanical fastener on the landing zone 78 and a second, cooperatingportion of the mechanical fastener on the fastener tab 44. For example,with a hook-and-loop fastener, the hook material 46 can be operablyconnected to the fastener tabs 44 and the loop material 80 can beoperably connected to the landing zone 78. Alternatively, the loopmaterial can be operably connected to the fastener tabs 44 and the hookmaterial can be operably connected to the landing zone.

In the various embodiments of the invention, a tape fastener tab 44 canbe located at either or both of lateral end regions 116 and 118 ofeither or both of the waistbands 38 and 40. The representatively shownembodiment, for example, has the fasteners tabs 44 located at the distalside edges of the rear waistband 40. In addition the backsheet layer 22can have an appointed fastener landing zone 78 disposed on an outwardsurface of the backsheet layer.

With reference to FIG. 1, for example, the article can include a systemof side panel members 90. In particular arrangements, each side panelmember 90 extends laterally from the opposed lateral ends of at leastone waistband portion of backsheet 22, such as the representativelyshown rear waistband portion 40, to provide terminal side sections ofthe article. In addition, each side panel can substantially span from alaterally extending, terminal waistband edge 106 to approximately thelocation of its associated and corresponding leg opening section of thediaper. Diaper 20, for example, has a laterally opposed pair of legopenings formed by appointed, medial sections of the shown pair oflongitudinally extending, side edge regions 110 (FIG. 1). Each sidepanel can span a longitudinal distance of at least about 4 cm,optionally may span a longitudinal distance of at least about 5 cm, andalternatively may span a distance of at least about 6 cm to provideimproved fit.

In the various configurations of the invention, the side panels may beintegrally formed with a selected diaper component. For example, sidepanels 90 can be integrally formed from the layer of material whichprovides backsheet layer 22, or may be integrally formed from thematerial employed to provide topsheet 24. In alternative configurations,the side panels 90 may be provided by one or more separate members thatare connected and assembled to the backsheet 22, to the topsheet 24, inbetween the backsheet and topsheet, and in various fixedly attachedcombinations of such assemblies.

In particular aspects of the invention, each of the side panels 90 maybe formed from a separately provided piece of material which is thensuitably assembled and attached to the selected front and/or rearwaistband portion of the diaper article. In the illustrated embodimentsof the invention, for example, each side panel 90 is attached to therear waistband portion of backsheet 22 along a side panel attachmentzone 94, and can be operably attached to either or both of the backsheetand topsheet components of the article. The shown configurations havethe inboard, attachment zone region of each side panel overlapped andlaminated with its corresponding, lateral end edge region of thewaistband section of the article. The side panels extend laterally toform a pair of opposed waist-flap sections of the diaper, and areattached with suitable connecting means, such as adhesive bonding,thermal bonding, ultrasonic bonding, clips, staples, sewing or the like.Desirably, the side panels extend laterally beyond the terminal sideedges of the backsheet layer and topsheet layer at the attachedwaistband section of the article.

The side panels 90 may be composed of a substantially non-elastomericmaterial, such as polymer films, woven fabrics, nonwoven fabrics or thelike, as well as combinations thereof. In particular aspects of theinvention, side panels 90 are composed of a substantially elastomericmaterial, such as a stretch-bonded-laminate (SBL) material, aneck-bonded-laminate (NBL) material, an elastomeric film, an elastomericfoam material, or the like, which is elastomerically stretchable atleast along the lateral direction 88. For example, suitable meltblownelastomeric fibrous webs for forming side panels 90 are described inU.S. Pat. No. 4,663,220 issued May 5, 1987 to T. Wisneski et al., theentire disclosure of which is hereby incorporated by reference. Examplesof composite fabrics comprising at least one layer of nonwoven textilefabric secured to a fibrous elastic layer are described in EuropeanPatent Application EP 0 217 032 A2 published on Apr. 8, 1987 which hasthe listed inventors of J. Taylor et al., the entire disclosure of whichis hereby incorporated by reference. Examples of NBL materials aredescribed in U.S. Pat. No. 5,226,992 issued Jul. 13, 1993 to Mormon, theentire disclosure of which is hereby incorporated by reference.

As previously mentioned, various suitable constructions can be employedto attach the side panels 90 to the selected waistband portions of thearticle. Particular examples of suitable constructions for securing apair of elastically stretchable members to the lateral, side portions ofan article to extend laterally outward beyond the laterally opposed sideregions of the outer cover and liner components of an article can befound in U.S. Pat. No. 4,938,753 issued Jul. 3, 1990 to P. VanGompel etal., the entire disclosure of which is hereby incorporated by referencein a manner that is consistent herewith. Where the side panels 90 arecomposed of a material which has been elasticized or otherwiseconstructed to be elastomerically stretchable, the elastomeric sidepanels can desirably provide an elongation at peak load of at leastabout 30 percent when subjected to a tensile force load of 0.33 poundsper lineal inch of the sample dimension that is measured perpendicularto the direction of the applied load (about 0.58 Newtons/cm).Alternatively, the elastomeric side panel material can provide anelongation of at least about 100%, and optionally can provide anelongation of at least about 300% to provide improved performance.

Each of the side panels 90 extends laterally from opposed lateral endsof at least one waistband section of the diaper 20. In the shownembodiment, each side panel extends laterally from opposed lateral endsof the rear waistband section of the backsheet 22. Each of the sidepanels includes a relatively outboard, terminal free end region 92 whichhas a longitudinally extending length dimension. Each side panel alsohas a laterally extending width dimension and a base region attachmentzone 94 which has a lapped, construction bond attachment to either orboth of the topsheet and backsheet layers. The side panels may have atapered or otherwise contoured shape in which the base length of theside panel attachment zone 94 is larger than the length of therelatively outboard distal end region 92. Alternatively, the length ofthe attachment zone 94 may be smaller than the length of the relativelyoutboard distal end region 92. Optionally, the side panels may have asubstantially rectangular shape or a substantially trapezoidal shape.

A stress beam section 98 can be constructed on each of the side panels90 along its outboard, free end region 92 to more evenly distributetensile stresses across the side panel area. The stress beam section isconfigured with a relatively high stiffness value, and in desiredconfigurations, the stress beam section extends along substantially theentire longitudinal length of the side panel outboard region 92. Afastening tab 44 can be connected to extend laterally from the stressbeam section of each of the side panels 90 for securing the waistbandsections of the article about a wearer during the use of the article.

Each fastening tab 44 can include a carrier layer 56 which interconnectsan inboard edge region of the selected fastening component, such as theshown hook member 46, to the outboard edge region of its associated andcorresponding side panel 90. The carrier layer has a laterally inboard,first side region and a laterally outboard, second side region. Thefirst side region is laminated, or otherwise connected and affixed, tothe side panel with an operable construction bond. The side panelmaterial, the carrier layer material and the configuration of theconstruction bond are constructed and arranged to form the operativestress beam section 98. Optionally, an additional layer of reinforcementmaterial may be included along the stress beam region to increase thestiffness of the beam and to further improve its ability to spreadstresses along the longitudinal dimension of the side panel. The inboardregion of the carrier layer 56 may have a longitudinal extent which isless than the longitudinal dimension of the outboard, free edge portion92 of the side panel 90. Alternatively, the carrier layer 56 can have alongitudinal extent which is substantially equal to (e.g. FIG. 1) orgreater than the longitudinal dimension of the outboard portion of theside panel.

The member of hook material 46 is laminated, or otherwise connected andaffixed, to the outboard region of the carrier layer with an operableconstruction attachment. In particular, the shown hook member 46 islaminated to a inward, bodyside surface of the carrier layer with thehook elements extending generally inwardly of the article. With theillustrated arrangement, the outboard, laterally distal edge of thesecond carrier edge region is coterminous with the outboard, laterallydistal edge of the hook member 46. Alternatively, the outboard,laterally distal edge of the second carrier edge region may be spacedlaterally inboard from the terminal, laterally distal edge of the hookmember 46. In either configuration, the laterally distal edge of thehook member 46 provides the laterally terminal edge of the article.

The longitudinally extending, relatively outboard edge of the side panelmember 90 may be spaced from the longitudinally extending, relativelyinboard edge of the selected fastening region by a carrier spacingdistance. More particularly, the outboard edge of the side panel member90 can also be spaced from the relatively inboard edge of the hookmember 46 by the carrier spacing distance. The spacing distanceoptionally has a lateral extent which is equal to or greater than thelateral extent of the fastening region. In addition, the inwardlyfacing, bodyside surface of the carrier layer 56 is constructed to havea limited, mechanical interengageability with the hook elements. As aresult, the fastener tab 44 can be folded along a longitudinallyextending fold line to selectively locate and configure the fasteningregion in a storage position with the hook elements placed and heldagainst the bodyside surface of the carrier layer 56. The level ofengagement between the hook material and the carrier layer need only beenough to maintain the storage position. For example, the engagement mayprovide a single-peak, peel force value within the range of about 1-50grams of force.

In particular configurations of the invention, the material of carrierlayer 56 can be composed of a substantially non-elastomeric material,such as polymer films, woven fabrics, nonwoven fabrics or the like, aswell as combinations thereof. Alternatively, the carrier web materialmay be composed of a substantially elastomeric material, such as astretch-bonded-laminate (SBL) material, a neck-bonded-laminate (NBL)material, an elastomeric film, an elastomeric foam material, or thelike, as well as combinations thereof. The elastomeric material iselastomerically stretchable at least along the lateral direction 88. Forexample, the carrier web material can be composed of aspunbond-meltblown-spunbond (SMS) fabric having a core of meltblownfibers sandwiched between two facing layers of spunbond fibers toprovide a total composite basis weight within the range of about 50-67g/m² (about 1.5-2 oz/yd²). As another example, the carrier web materialmay be entirely composed of a nonwoven spunbond fabric having a basisweight within the range of about 50-67 g/m² (about 1.5-2 oz/yd²).

The mechanical fasteners cooperatively employed with the variousconfigurations of the invention can be provided by mechanical-typefasteners such as hooks, buckles, snaps, buttons and the like, whichinclude cooperating and complementary, mechanically interlockingcomponents. In particular aspects of the invention, the fastening meanscan be provided by a hook-and-loop fastener system, a mushroom-and-loopfastener system, or the like (collectively referred to as hook-and-loopfasteners). Such fastening systems generally comprise a “hook” orhook-like, male component, and a cooperating “loop” or loop-like, femalecomponent which engages and releasably interconnects with the hookcomponent. Desirably, the interconnection is selectively releasable.Conventional systems are, for example, available under the VELCROtrademark.

Examples of suitable hook-and-loop fastening systems are described inU.S. Pat. No. 5,019,073 issued May 28, 1991 to T. Roessler et al., theentire disclosure of which is hereby incorporated by reference in amanner that is consistent herewith. Other examples of hook-and-loopfastening systems are described in U.S. patent application Ser. No.366,080 entitled HIGH-PEEL TAB FASTENER, filed Dec. 28, 1994 by G.Zehner et al. (attorney docket No. 11,571) which issued as U.S. Pat. No.5,605,735; and U.S. patent application Ser. No. 421,640 entitledMULTI-ATTACHMENT FASTENING SYSTEM, filed Apr. 13, 1995 by P. VanGompelet al. which corresponds to U.S. Pat. No. 6,030,373 issued Feb. 29,2000; the entire disclosures of which are hereby incorporated byreference in a manner that is consistent herewith. Examples of fasteningtabs constructed with a carrier layer 56 are described in U.S. patentapplication Ser. No. 08/603,477 of A. Long et al., entitled MECHANICALFASTENING SYSTEM WITH GRIP TAB and filed Mar. 6, 1996 (attorney docketNo. 12,563) which issued as U.S. Pat. No. 5,624,429, the entiredisclosure of which is hereby incorporated by reference in a mannerwhich is consistent herewith.

In a typical configuration of a hook-and-loop fastening system, the hookmaterial member 46 is operably connected to the fastening tab 44, andthe loop material 80 is employed to construct at least one cooperatinglanding zone 78. The landing zone, for example, can be suitablypositioned on the exposed, outward-side surface of the backsheet 22. Aspreviously mentioned, an alternative configuration of the hook-and-loopfastening system may have the loop material secured to the fastener tab44 and may have the hook material employed to form the landing zone 78.

In particular aspects of the invention, the hook material member 46 canbe of the type referred to as micro-hook material. A suitable micro-hookmaterial is distributed under the designation CS200 and is availablefrom 3M Company, a business having offices in St. Paul, Minn. Themicro-hook material can have hooks in the shape of mushroom “caps”, andcan be configured with a hook density of about 1600 hooks per squareinch; a hook height which is within the range of about 0.033-0.097 cm(about 0.013 to 0.038 inch); and a cap width which is within the rangeof about 0.025-0.033 cm (about 0.01 to 0.013 inch). The hooks areattached to a base film substrate having a thickness of about0.0076-0.01 cm (about 0.003-0.004 inch) and a Gurley stiffness of about15 mgf (milligrams-force).

Another suitable micro-hook material is distributed under thedesignation VELCRO CFM-29 1058, and is available from VELCRO U.S.A.,Inc., a business having offices in Manchester, N.H. The micro-hookmaterial can have hooks in the shape of angled hook elements, and can beconfigured with a hook density of about 264 hooks per square centimeter(about 1700 hooks per square inch); a hook height which is within therange of about 0.030-0.063 cm (about 0.012-0.025 inch); and a hook widthwhich is within the range of about 0.007 to 0.022 cm (about 0.003 to0.009 inch). The hook elements are coextruded with a base layersubstrate having a thickness of about 0.0076-0.008 cm (about0.003-0.0035 inch) and the member of hook material has a Gurleystiffness of about 12 mgf (12 Gurley Units).

For the purposes of the present invention, the various stiffness valuesare determined with respect to a bending moment produced by a forcewhich is directed perpendicular to the plane substantially defined bythe length and width of the component being tested. A suitable techniquefor determining the stiffness values described herein is a GurleyStiffness test, a description of which is set forth in TAPPI StandardTest T 543 om-94 (Bending Resistance of Paper (Gurley type tester)). Asuitable testing apparatus is a Gurley Digital Stiffness Tester; Model4171-D manufactured by Teledyne Gurley, a business having offices inTroy, N.Y.

In the various configurations of the invention, the loop material can beprovided by a nonwoven, woven or knit fabric. For example, a suitableloop material fabric can be composed of a 2 bar, warp knit fabric of thetype available from Guilford Mills, Inc., Greensboro, N.C. under thetrade designation #34285, as well other of knit fabrics. Suitable loopmaterials are also available from the 3M Company, which has distributeda nylon woven loop under their SCOTCHMATE brand. The 3M Company has alsodistributed a liner-less loop web with adhesive on the backside of theweb, and 3M knitted loop tape.

In particular aspects of the invention, the loop material need not belimited to a discrete landing zone patch. Instead the loop material can,for example, be provided by a substantially continuous, outer fibrouslayer which is integrated to extend over substantially the total exposedsurface area of a cloth-like outer cover employed with the diaper 20.The resultant, cloth-like backsheet 22 can thereby provide the loopmaterial for an operative “fasten anywhere” mechanical fastening system.As a practical matter, the area extent of the loop material will dependon the cost of the material.

The fastening elements in the various constructions of the invention maybe operably attached to its base layer by employing any one or more ofthe attachment mechanisms employed to construct and hold together thevarious other components of the article of the invention. Desirably, thefastening elements in the various fastening regions, may be integrallyformed, such as by molding, co-extrusion or the like, along with theassociated base layer. The base layer and the mechanical fasteningelements can be formed from substantially the same polymer material, andthere need not be a discrete step of attaching the fastening elements toan initially separate hook base layer. In the representatively shownconfigurations of the primary fastening region, for example, the hookelements can be integrally formed simultaneously with the hook baselayer by coextruding the base layer and hook elements from substantiallythe same polymer material.

It should be readily appreciated that the strength of the attachment orother interconnection between the base layer and the attached fasteningcomponent should be greater than the peak force required to remove thefastener tab 44 from its releasable securement to the appointed landingzone of the article.

CALCULATION AND TESTING PROCEDURES Partial Saturation ThicknessProcedure

The thickness height (h) of each layer in its partially saturated statecan be determined by again using the inputs as determined above and thefollowing procedure:

Scope:

The thickness (h) of each layer region in a partially saturated state isdetermined.

Equipment and Materials:

Glass petri dish (100×15 mm—Corning Number 3160-101—Fisher ScientificCatalog Number 08-747C).

Blood bank saline solution, such as catalogue No. 8504 Blood bank salineobtained from Stevens Scientific, a division of Cornwell Corporation, abusiness having offices located at Riverdale, N.J.; or a substantialequivalent.

Thickness tester with 0.05 psi (0.345 KPa) platen of 3 inch (7.62 cm)diameter.

Die cutter—3 inch (7.62 cm) diameter circle.

Weighing scale.

Laboratory timer.

Test Procedure

Die cut a 3 inch (7.62 cm) diameter sample of the material to be tested.

Calculate the saturation (grams fluid/grams sample) of the layer basedon a 0.6 g/cm² saturation of the absorbent and superabsorbent mass, andemploying the technique discussed in the Flow Conductance Calculation.

Weigh the dry sample and record the weight.

Calculate the amount of liquid saline solution to be added to the sampleby multiplying the dry sample weight by the desired saturation level.

Dispense the calculated amount of liquid into a petri dish on flatsurface to provide a uniform distribution of liquid to the sample.

Place the sample into the petri dish such that the sample remains flat.Start the timer.

After 30 minutes have elapsed, remove the sample from the petri dish.

Measure the thickness of the sample (in mm) under a restraining pressureof 0.05 psi (0.34 KPa), and record the thickness.

The values of the partial saturation thickness height (h) can the beemployed in the equations employed to calculate the Flow ConductanceValue for the absorbent composite system.

Flow Conductance Calculation

The Flow Conductance of the absorbent core at a liquid loading of 0.6g/cm² of absorbent is used to reflect the intake capability of anabsorbent core structure when the core is in its partially saturatedstate. The Flow Conductance can be described by the following equation:

Flow Conductance Value=K₁h₁+K₂h₂+K₃h₃+ . . .

Where:

K=the permeability of each layer at a given saturation.

h=the thickness of each layer at a given saturation.

The permeability (K) of each layer in the core can be computed asfollows: Each layer in the absorbent core-is a combinations ofsubstantially non swelling fibers and superabsorbent particles, fibersor flakes.

Expressions for the permeability of a collection of cylinders orientedrandomly and for a collection of spheres are:

For cylindrical and other regular or irregular, elongated fiber shapes:$K = {\left( \frac{0.30}{\left( \frac{SA}{V} \right)^{2}} \right)\left( {1 - ɛ} \right)\left( \frac{ɛ}{1 - ɛ} \right)^{2.5}}$

For generally spherical, and other regular or irregular particle shapes:$K = {\left( \frac{0.3555}{\left( \frac{SA}{V} \right)^{2}} \right)\left( {1 - ɛ} \right)\left( \frac{ɛ}{1 - ɛ} \right)^{2.35}}$

where SA/V is the surface area to volume ratio of the solid portion incm⁻¹ and the porosity, ε, is the ratio of the pore volume to the totalvolume of the entire medium. The basis for the above permeabilityexpressions comes from Happel and Brenner, Low Reynolds NumberHydrodynamics, Noordhoff International Publishing (1973). Expressions ofpermeability for the cylinders and spheres derived in that work were fitto simpler forms, as shown above, to obtain the value of the exponentand the multiplier.

It has been observed that essentially all the liquid delivered duringthe first insult is imbibed by the superabsorbent before the secondinsult is delivered. Accordingly, for the purpose of calculating thepermeability value employed in the flow conductance computations, all ofthe above specified liquid (0.6 g/cm²) is considered to be within thesuperabsorbent. Therefore, in calculating the values for porosity, ε,and the surface area per volume ratios for the superabsorbents, theliquid volume is included as part of the solid volume. Thus, theporosity, ε, of the material is given by:

ε=1−[(solid volume+liquid volume)/(total volume occupied by wettedsample)];

where the total volume occupied by the wetted sample is determined bythe area of the sample multiplied by the thickness of the sample.Thickness of the sample can be determined by Partial SaturationThickness Procedure set forth in the present description.

The surface area per volume (SA/V) terms used in the permeabilityequations for the various components are calculated using the surfacearea per volume expressions for either fibers or particles, asappropriate for the morphology of the individual component. For fibers,the surface area to volume ratio is equal to the perimeter to arearatio, p/a, of a cross-section taken perpendicular to the longitudinalaxis of the cylinders. For a cylinder with a circular cross-section, forexample:

SA/V=p/a=2/r;

where r is the radius of the cylinder cross-section in cm.

For ribbon-like shapes; i.e., those with approximately rectangularcross-section:$\frac{SA}{V} = {\frac{p}{a} = \frac{2 \cdot \left( {{width} + {thickness}} \right)}{\left( {{width} \cdot {thickness}} \right)}}$

For fibers with more complex cross-sectional shapes, the perimeter toarea ratios can be determined by microscopic techniques well known inthe art. For example, see E. E. Underwood, Quantitative Stereology,Addison Wesley Publishing Co. (1970).

In these computations the surface area to volume ratio of substantiallynon-swelling fibers can be determined by using a “SA/V” value (for thefiber's surface area to volume ratio) which is appropriate to thatfiber's cross-sectional shape. For example, fluff fibers are generallyribbon-like, with a rectangular cross-sectional shape. For a fluff fiberwith a thickness of 8 microns (0.0008 cm) and a width of 40 microns(0.0040 cm), for example, the surface area per volume ratio is$\frac{SA}{V} = {\frac{p}{a} = \frac{2 \cdot \left( {8 + 40} \right) \cdot 10^{- 4}}{\left( {\left( {8 \cdot 40} \right) \cdot 10^{- 8}} \right)}}$

 SA/V=3000 cm⁻¹

The superabsorbent morphology may be particulate, fibrous, flake-like orcombinations thereof. Furthermore, superabsorbent swellingcharacteristics may be isotropic or anisotropic. The majority of thecommercially available superabsorbents are in the form of particleswhich swell substantially isotropically. Such superabsorbent particlescan be treated as spheres in the present computations. When the particlesizes are all substantially identical, the surface area to volume ratiofor a sphere can be used to estimate the superabsorbents surface area tovolume ratio. The surface area to volume ratio for a sphere is given by

SA/V=3/r

where r is the radius of the sphere in cm.

However, superabsorbent materials may be composed of a distribution ofparticle sizes. When this distribution is substantially monomodal, thecount-weighted surface area to volume can be used. For a givendistribution, this value can be calculated as follows:$\frac{SA}{V} = \frac{3 \cdot {\sum\limits_{i}\left( {r_{i}^{2} \cdot n_{i}} \right)}}{\sum\limits_{i}\left( {r_{i}^{3} \cdot n_{i}} \right)}$

where

r_(i)=mid point of the particle radius range of the i^(th) portion, incm.

n_(i)=the number of particles within the i^(th) portion$n_{i} = \frac{m_{i}}{\left\lbrack {\rho_{SAP} \cdot \left( \frac{4}{3} \right) \cdot \pi \cdot r_{i}^{3}} \right\rbrack}$

and

m_(i)=mass fraction of particle within the i^(th) portion in grams.

ρ_(SAP)=density of the dry superabsorbent solid in g/cc.

If the particle size distribution is multi-modal, e.g. bi-modal, aseparate permeability for each modal group should be used in theself-consistent calculation of the permeability of the compositematerial detailed below. In this instance, a count-weighted surface areato volume ratio should be calculated for each modal group, as describedabove. Typically, at least 6 to 8 different particle size fractionsshould be used to estimate the particle size distribution of thesuperabsorbent.

The swelling of the superabsorbent with the absorption of liquid furthercomplicates the process of incorporating the contributions of thesuperabsorbent into the determination of the composite permeability. Inparticular, the size, and therefore surface area to volume ratio, of thesuperabsorbent will depend on the level of saturation of thesuperabsorbent. The relationship for the surface area to volume ratio ofan isotropically swelling superabsorbent particle, as a function of itsliquid content, is$\left( \frac{SA}{V} \right)_{wet} = \frac{\left( \frac{SA}{V} \right)_{dry}}{\left\lbrack {1 + \left( \frac{S \cdot \rho_{SAP}}{\rho_{l}} \right)} \right\rbrack^{(\frac{1}{3})}}$

where

(SA/V)_(wet)=surface area per volume ratio of the wet superabsorbent incm⁻¹

S=saturation of the superabsorbent expressed as grams of liquid per gramof superabsorbent

ρ_(SAP)=density of the dry SAP in g/cc

ρ_(l)=density of the liquid in g/cc

(SA/V)_(dry)=surface area per volume ratio of the dry SAP in cm⁻¹

Superabsorbent materials may also be present in fibrous form. It hasbeen observed that, in general, the fibrous superabsorbents will swellanisotropically. In particular, the increase in fiber volume withincreased liquid content is primarily radial, with the fiber lengthremaining relatively constant. In such cases, the surface area to volumeratio of the swollen superabsorbent fiber is given by$\left( \frac{SA}{V} \right)_{wet} = \frac{\left( \frac{SA}{V} \right)_{dry}}{\left\lbrack {1 + \left( \frac{S \cdot \rho_{SAP}}{\rho_{l}} \right)} \right\rbrack^{(\frac{1}{2})}}$

With the above relationships for surface area to volume ratio as afunction of liquid content in the superabsorbent, the surface area tovolume ratio for superabsorbent with a particular liquid content can becalculated. Before the surface area to volume ratio for eachsuperabsorbent can be calculated for use in the permeability equationsgiven above, the level of saturation of each superabsorbent in eachlayer should be determined. The following discussion describes themethod used to estimate the level of saturation of each of thesuperabsorbents present in the absorbent core.

It has been observed that, in the time interval between delivery of thefirst and second liquid insults to the product, the liquid isessentially completely taken up by the superabsorbents in the system.Furthermore it has been observed that the liquid delivered during thefirst insult partitions between the superabsorbent materials inaccordance with their relative amounts and liquid pickup rates. For theliquid loading specified above (0.6 g/cm²) the saturation, S_(j),expressed as grams of liquid amount per gram of superabsorbent in eachsuperabsorbent can be calculated as follows:$S_{j} = \frac{\left( {f_{p_{j}} \cdot 0.6} \right)}{\left( {{bw}_{j} \cdot 10^{- 4}} \right)}$

bw_(j)=basis weight of the j^(th) super absorbent in grams/square meter

f_(pj)=liquid partition factor for the j^(th) super absorbent

Liquid partition factors, f_(pj), are calculated for each superabsorbentcomponent based on the relative rates and amounts of the varioussuperabsorbent components.$f_{p_{j}} = \frac{f_{R_{j}} \cdot {bw}_{j}}{\sum\limits_{j}\left( {f_{R_{j}} \cdot {bw}_{j}} \right)}$

where

bw_(j)=basis weight of the j^(th) superabsorbent in grams/square meter,

f_(Rj)=the relative rate factor of the j^(th) superabsorbent.

The relative rate factor, f_(Rj), for each superabsorbent is given by

f_(Rj)=τ1/τj

where

τ_(j)=time required for the j^(th) super absorbent to absorb 60% of itsequilibrium capacity on the absorbency under no load (FAUZL) testdescribed herein.

For purposes of illustrating the method, consider an example having atwo layer absorbent with the following compositions:

Layer region 1: Superabsorbent type 1 of 400 micron count-weightedparticle size at 120 gsm (grams per square meter),

τ₁=5 min,

Wood pulp fluff at 120 gsm with 8 micron by 40 micron fibercross-section,

Measured thickness at the saturation level specified below=0.55 cm.

Layer region 2: Superabsorbent type 2 of 400 micron count-weightedparticle size at 150 gsm,

τ₂=10 min,

Wood pulp fluff at 300 gsm with 8 micron by 40 micron fibercross-section,

Measured thickness at the saturation level specified below=0.51 cm.

For the superabsorbents used in these layers

f_(R1)=5/5=1

f_(R2)=5/10=0.5

and$f_{p_{1}} = {\frac{1 \cdot 120}{\left( {{1 \cdot 120} + {0.5 \cdot 150}} \right)} = 0.62}$$f_{p_{2}} = {\frac{0.5 \cdot 150}{\left( {{1 \cdot 120} + {0.5 \cdot 150}} \right)} = 0.38}$

so that$S_{1} = {\frac{\left( {0.62 \cdot 0.6} \right)}{\left( {120 \cdot 10^{- 4}} \right)} = {31\frac{g}{g}}}$$S_{2} = {\frac{\left( {0.38 \cdot 0.6} \right)}{\left( {150 \cdot 10^{- 4}} \right)} = {15.2\frac{g}{g}}}$

The above computations are appropriate when the total equilibrium FAUZLsuperabsorbent capacities are not exceeded at the specified loading of0.6 g/cm². If the capacity of a particular superabsorbent material isexceeded under these circumstances, its saturation is set to theequilibrium value and the excess liquid is assumed to reside in theother superabsorbents in a manner consistent with the descriptions givenherein.

Based on the amounts of liquid located within the superabsorbentparticles, the surface area to volume ratio of the swollen particles orfibers in each layer can be calculated using the appropriate surfacearea to volume ratio equations given above for the swollen particlesand/or fibers. The permeability equation identified for spheres shouldbe used for the particulate superabsorbents, and the permeabilityequation identified for cylinders should be used for fibroussuperabsorbents.

In this particular example the superabsorbents are in particulate formso their surface area to volume ratios when the core contains 0.6 g/cm²liquid are as follows:

Layer region 1 superabsorbent: $\begin{matrix}{\left( \frac{SA}{V} \right)_{{SAP}\quad 1} = \frac{\left( \frac{SA}{V} \right)_{dry}}{\left\lbrack {1 + \left( \frac{S \cdot \rho_{SAP}}{\rho_{l}} \right)} \right\rbrack^{(\frac{1}{3})}}} \\{= {\frac{3/\left( {200 \cdot 10^{- 4}} \right)}{\left\lbrack {1 + \left( \frac{31 \cdot 1.48}{1} \right)} \right\rbrack^{(\frac{1}{3})}} = {41.6\quad {cm}^{- 1}}}}\end{matrix}$

Layer region 2 superabsorbent: $\begin{matrix}{\left( \frac{SA}{V} \right)_{{SAP}\quad 2} = \frac{\left( \frac{SA}{V} \right)_{dry}}{\left\lbrack {1 + \left( \frac{S \cdot \rho_{SAP}}{\rho_{l}} \right)} \right\rbrack^{(\frac{1}{3})}}} \\{= {\frac{3/\left( {200 \cdot 10^{- 4}} \right)}{\left\lbrack {1 + \left( \frac{15.2 \cdot 1.48}{1} \right)} \right\rbrack^{(\frac{1}{3})}} = {52.4\quad {cm}^{- 1}}}}\end{matrix}$

Fibrous woodpulp fluff component used in both layers:$\frac{SA}{V} = {\frac{p}{a} = \frac{2 \cdot \left( {8 + 40} \right) \cdot 10^{- 4}}{\left( {\left( {8 \cdot 40} \right) \cdot 10^{- 8}} \right)}}$

 SA/V=3000 cm⁻¹

One can now set up appropriate equations for determining thepermeability of each of the components within each composite layerregion employed to construct the absorbent core by using the aboveexpressions for the permeabilities of collections of fibers orcollections of particles. However, the above-expressions for thepermeabilities of the collections of fibers and/or particles are validonly if the entire porous medium consists solely of monodisperse fibersor particles. When both fibers and particles are present in a medium ofspecified porosity, the above expressions are combined. The method usedto combine these two is in accordance the self-consistent methodoutlined in A. L. Berdichevsky and Z. Cai, “Preform PermeabilityPredictions by Self-consistent Method and Finite Element Simulation”,Polymer Composites, 14(2), (1993).

For the present description, the basic premise behind theself-consistent method is that the permeability is substantiallyhomogeneous throughout the porous medium. Therefore, the local porosityvalues corresponding to the fibers and the particles are determined suchthat their local permeabilities are equal. The above computation issubject to the constraint that the overall porosity (ε_(comp)) of thestructure be maintained at the specified value which is determined fromthe measured sample area and thickness, as described above. The simplestcomposite composition consists of two components. In this case, twopermeability equations will be required for the self-consistentcalculation of composite permeability. For the present two layer exampledescribed above the permeability equations to be used in theself-consistent composite permeability computation are as follows.

The permeability equations for layer 1 and layer 2 are:

Layer region 1:${{fiber}\quad K_{{fiber}\quad 1}} = {\left( \frac{0.30}{(3000)^{2}} \right)\left( {1 - ɛ_{{fiber}\quad 1}} \right)\left( \frac{ɛ_{{fiber}\quad 1}}{1 - ɛ_{{fiber}\quad 1}} \right)^{2.5}}$${{superabsorbent}\quad K_{{SAP}\quad 1}} = {\left( \frac{0.3555}{(41.6)^{2}} \right)\left( {1 - ɛ_{{SAP}\quad 1}} \right)\left( \frac{ɛ_{{SAP}\quad 1}}{1 - ɛ_{{SAP}\quad 1}} \right)^{2.35}}$

Layer region 2:${{fiber}\quad K_{{fiber}\quad 2}} = {\left( \frac{0.30}{(3000)^{2}} \right)\left( {1 - ɛ_{{fiber}\quad 2}} \right)\left( \frac{ɛ_{{fiber}\quad 2}}{1 - ɛ_{{fiber}\quad 2}} \right)^{2.5}}$${{superabsorbent}\quad K_{{SAP}\quad 2}} = {\left( \frac{0.3555}{(52.4)^{2}} \right)\left( {1 - ɛ_{{SAP}\quad 2}} \right)\left( \frac{ɛ_{{SAP}\quad 2}}{1 - ɛ_{{SAP}\quad 2}} \right)^{2.35}}$

where ε_(fiber1), ε_(SAP1), ε_(fiber2) and ε_(SAP2) correspond to thelocal porosity values of the fiber and superabsorbents in layers 1 and2, respectively. The combination of the local porosities must yield thecorrect overall porosity obtained from thickness measurements describedearlier, namely$ɛ_{comp} = {1 - \frac{{bwt}_{comp} \cdot 10^{- 4} \cdot \left\lbrack {{\sum\limits_{k}\left( \frac{f_{k}}{\rho_{k}} \right)} + {\sum\limits_{j}\left( \frac{f_{j}}{\rho_{j}} \right)} + {\sum\limits_{j}\left( \frac{S_{j} \cdot f_{j}}{\rho_{l}} \right)}} \right\rbrack}{h_{comp}}}$

where:

bwt_(comp)=basis weight of the composite in grams per square meter

f_(k)=mass fraction of the composite provided by the k^(th) fiber

f_(j)=mass fraction of the composite provided by the j^(th)superabsorbent

such that ${{\sum\limits_{k}f_{k}} + {\sum\limits_{j}f_{j}}} = 1$

and

ρ_(k)=density of the k^(th) fiber,

ρ_(j)=density of the j^(th) superabsorbent,

ρ_(l)=density of the liquid,

S_(j)=level of saturation of the j^(th) superabsorbent in grams liquidper gram of that superabsorbent,

h_(comp)=thickness (cm) of the composite at the level of liquid loadingequal to the total liquid load in the composite, where the total liquidload in the composite is given by:${bwt}_{comp} \cdot 10^{- 4} \cdot {\sum\limits_{j}{\left( {S_{j} \cdot f_{j}} \right).}}$

For the two layer example given above with only one type of fiber andone type of superabsorbent in each layer, the density of the fibercomponent in both layers is 1.5 g/cc, the density of the superabsorbentcomponent in both layers is 1.48 g/cc and the superabsorbent massfractions, liquid loadings, and composite heights of each layer are asspecified above. The overall porosity values are as follows:

Layer region 1:$ɛ = {{1 - \frac{{240 \cdot 10^{- 4}}\left( {{0.5/1.5} + {0.5/1.48} + {31~0.5}} \right)}{0.55}} = 0.29}$

Layer region 2:$ɛ = {{1 - \frac{{450 \cdot 10^{- 4}}\left( {{0.67/1.5} + {0.33/1.48} + {15.2 \cdot 0.33}} \right)}{0.51}} = 0.50}$

The values for the permeability of the two layers after conducting theself-consistent calculation are:

Layer region 1:

K=1.6·10⁻⁶ cm²

Layer region 2:

K=1.1·10⁻⁶ cm²

This simple two layer case serves to illustrate the principle compositepermeability calculation. However, the composites used in constructingthe absorbent core of this invention may include more than twocomponents. In such instances, it is necessary to include a permeabilityequation for each component within a given composite layer region whenexecuting the self-consistent composite permeability computation forthat layer region. For example, if a composite layer region contains twofiber types and two superabsorbents, four permeability equations will berequired in the computation of the composite permeability when employingthe self-consistent method.

With the composite permeabilities and thicknesses (height, h) determinedfor each layer region of the absorbent core in its partially saturatedstate, as described above, it is now possible to calculate the FlowConductance Value for the system. As described previously,

Flow Conductance Value=K₁h₁+K₂h₂+K₃h₃+ . . .

So, for the two layer example given above: $\begin{matrix}{{{Flow}\quad {Conductance}\quad {Value}} = {\left( {1.6*10^{- 6}*0.55} \right) + \left( {1.1*10^{- 6}*0.51} \right)}} \\{= {1.4*10^{- 6}\quad {cm}^{3}}}\end{matrix}$

While the above calculations of the permeability and flow conductanceare illustrated for a two layer structure whose layers each contain oneisotropically swelling particulate superabsorbent and one fiber type,the calculation of the flow conductance can be extended to casesincluding more than two layers, and the calculation of the permeability,K, can be readily adapted for more complex materials, in accordance withthe description set forth herein.

Liquid Wicking Value

Scope

This test is used to determine the capability of an absorbent materialto remove liquid from the target area.

Summary

Determine the amount of liquid to be applied to a sample based on theliquid partitioning calculations. Allow the sample to absorb the liquidfrom a reservoir and determine the amount of liquid that has beenremoved from the target area.

Equipment and Materials

A 21 cm by 21 cm piece of Plexiglas, or similar material, of 5 mm orless thickness.

Suitable liquid reservoir.

Lab balance.

A sample support for holding the absorbent sample vertical during theaddition of liquid to the sample.

Binder clips for holding sample to the Plexiglas, such as Medium binderclip No. 10050 from IDL Corporation, Caristadt, N.J.

Laboratory oven at 150 degrees centigrade.

Test Materials

Test liquid, saline solution; Recommended Saline, Blood bank salinesolution, such as Catalog No. 8504 Blood bank saline obtained fromStephens Scientific, a division of the Cornwell Corporation, a businesshaving offices located at Riverdale, N.J.; or a substantial equivalent.

Sample Preparation

Remove the sample layer region from the product, or otherwise prepare asample having the same shape as will exist in the product. Each layershould be separated and tested separately.

Mark the target location with a permanent ink marker. The targetlocation of the layer being tested is determined when the layer is atits intended position in the absorbent core. The target location is at alaterally centered area which is located inboard from the terminal frontedge of the furthest frontward extending absorbent layer of theabsorbent core by a distance equal to 36% of the overall length of theabsorbent core. Accordingly, the furthest frontward extending absorbentlayer of the absorbent core is not necessarily the layer being tested.

Mark the target area on the sample with a permanent ink marker. Thetarget area of the sample layer being tested is determined when thelayer is at its intended position in the absorbent core. The target areaof the test sample layer is the area of the sample layer which liesbetween two, laterally extending lines. The first line is positionedinboard from the terminal front edge of the furthest frontward extendingabsorbent layer of the absorbent core by a distance equal to 24% of theoverall length of the absorbent core. The second line is positionedinboard from the terminal front edge of the furthest frontward extendingabsorbent layer of the absorbent core by a distance equal to 59% of theoverall length of the absorbent core. Both lines are substantiallyperpendicular to the longitudinally extending centerline of theabsorbent core. If both of these two target area lines fall outside theboundary edges of the absorbent sample being tested, then the LiquidWicking Value of the sample being tested will be zero by definition.

Calculate the amount of liquid to be absorbed by the sample by using theliquid partitioning calculations, as set forth in the description forcalculating the Flow Conductance Value. However, rather than calculatingthe SAP saturation for each layer, determine only the amount of liquidpredicted to be within each layer. This can be done by using thefollowing equation:

Liquid in Layer “j”=(f_(pj))* 1.0 g/cm² * Target Zone Surface Area.

(e.g., for the example given with the description of the determinationof the Flow Conductance Value; 61.6 grams of liquid in layer region 1,and 38.4 grams of liquid in layer region 2, when employing a 100 cm²target zone surface area).

Set-up Procedure

Place the sample on the Plexiglas sample holder such that the targetlocation is directly at the bottom of the apparatus.

Fill the liquid reservoir to a point approximately 1 cm from the top.

Place the reservoir on the lab balance.

Test Procedure

Tare the balance.

Suspend the sample in the reservoir such that the liquid touches theabsorbent system. Fluid contact must be maintained throughout theprocedure.

Using the lab balance as a reference, allow the absorbent composite toabsorb the quantity of fluid determined in the previous calculations.Remove the sample from the reservoir when the sample has absorbed anamount equal to that based on fluid partitioning calculations ±5 gms.

Allow the sample to remain undisturbed for five minutes in the verticalposition.

Cut the sample at the target area marks and remove the center portion.Weigh the remaining sections.

Dry the remaining sections in an oven overnight.

Weigh the dry samples and subtract this weight from the wet weight todetermine the amount of liquid which moved out from the target area.Divide the amount of liquid removed from the target area (i.e. theamount measured by the previous step) by the total amount of liquidapplied to the target area (e.g. target zone surface area in cm²,multiplied by 1 g of liquid per cm²); and multiply that result by 100.This is the Liquid Wicking Value of the layer region.

The Liquid Wicking Value of a multi-layer absorbent composite is thelargest Liquid Wicking Value provided any one of the layers. Forexample, the Liquid Wicking Value of a two-layer, absorbent composite isthe larger of the two Liquid Wicking Values provided by the two layers.

Combined Conductance-Wicking Value (C)

The Combined Conductance-Wicking Value can be determined in accordancewith the following formula:$C = {({FCV}) + \frac{({LWV})}{\left( {3 \cdot 10^{6}} \right)}}$

where:

FCV=Flow Conductance Value in units of cm³;

LWV=Liquid Wicking Value in percent; and

(3·10⁶) has the units of cm⁻³.

Modified Absorbency Under Load (MAUL)

Scope

This test is designed to measure the ability of a particulatesuperabsorbent polymer (SAP) to absorb saline while under a constantload of 0.3 psi (2.07 KPa). More specifically, the test measures theamount of saline absorbed by 0.160 grams of superabsorbent polymer,which has been prescreened through a U.S. std. #30 mesh and retained ona U.S. std. #50 mesh., when it is confined within a 5.07 cm² area undera pressure of 0.3 psi (2.07 KPa). A suitable testing device isrepresentatively shown in FIGS. 10 through 14.

Equipment and Materials

Electronic balance, accurate to 0.001 gram (200 gram minimum capacity).

Cylinder group: 1 inch (25.4 mm) inside diameter, plastic cylinder (120)with a 100 mesh stainless steel screen affixed to the cylinder bottom;4.4 gram plastic piston disk (122) with a 0.995 inch (25.27 mm)diameter. The piston disk diameter is 0.005 inch (0.13 mm) smaller thanthe inside diameter of the cylinder. See FIG. 11.

100 gram weight (124) having a 0.984 inch (25 mm) diameter.

0.9% (wt/wt) NaCl solution (Blood Bank Saline).

Saline basin (126).

Timer (140) capable of reading 200 minutes at one second intervals.

Weighing paper.

U.S. Standard Testing Sieve (A.S.T.M. E-11 Specification) groupingincluding one receiver, one U.S. std. #30 mesh, one U.S. std. #50 mesh,and one lid. A tapping device is positioned above the sample to providea consistent tapping onto the supporting piston disk, as illustrated inFIGS. 10 and 12. This tapping dislodges any trapped air surrounding theSAP and ensures that liquid wets the SAP surface. In this setup, a motor(128) rotates a shaft which drives a rod (130) along an up and downstroke. At the lower end of the rod is a rubber foot (132) which has adiameter of 13 mm, as illustrated in FIG. 12. The shaft stroke is 3 cmand it completes a full up and down stroke cycle every 0.7 seconds. Themaximum pressure that the piston disk will apply to the SAP at impact is0.16 psi (0.11 KPa).

With reference to FIG. 10, a fixture (134) has a vacuum port (136) thatallows for the evacuation of interstitial liquid from the sample. Theport accommodates the base of the cylinder group. When the cylindergroup containing the sample is placed on the fixture, the free liquid isremoved from between the sample particles. A suitable pump (138) appliesa vacuum pressure applied to the sample of 100 torr (13.3 KPa) or less.

FIG. 10 shows the entire test setup. It should be noted that electronictimers (140) are desirably employed to control the duration of thetapping and vacuum devices. In this setup the tapping device also restsonto a slide (142) which would allow movement between multiple samples.

Procedure

1. Using the U.S.A. Standard Testing Sieve grouping, sieve enoughsuperabsorbent to provide a minimum of 0.160 grams that passes throughthe #30 mesh screen and is retained on the #50 mesh screen.

2. Weigh out 0.160 grams (±0.001 grams) of sieved superabsorbent fromstep 1 onto the pre-tared weighing paper.

3. Slowly pour the superabsorbent into the cylinder having the 100 meshbottom. Avoid allowing the SAP to contact the sides of the cylinderbecause granules may adhere. Gently tap the cylinder until the granulesare evenly distributed on the screen.

4. Place the plastic piston in the cylinder. Weigh this cylinder groupand record the weight as the “cylinder group superabsorbent amount.”

5. Fill the saline basin to a 1 cm height with the blood bank saline.

6. Place the cylinder group in the saline basin, directly below theshaft of the tapping device and start the timer. Start the tappingdevice to tap for an eight second period.

7. Within 5 seconds of the end of the eight second tapping period, placethe 100 g weight on top of the cylinder group piston, as illustrated inFIG. 11.

8. 200 minutes after the cylinder is placed into the basin, remove thecylinder group and weight, place the cylinder group and 100 g weightonto the vacuum platform, as illustrated in FIG. 13. Apply the vacuumfor a 6 second period.

9. Remove the 100 gram weight from the cylinder group, weigh thecylinder group, and record the weight.

Results and Analysis

For each test, calculate the grams of saline absorbed per gram of SAP.This is the MAUL value for the superabsorbent.

Flooded Absorbency Under Zero Load (FAUZL)

Scope

This test is designed to measure the saline absorption rate ofparticulate superabsorbent polymer (SAP). The test measures, as afunction of time, the amount of saline absorbed by 0.160 grams ofsuperabsorbent polymer (starting either dry or presaturated) when it isconfined within a 5.07 cm² area under a determined nominal pressure of0.01 psi (0.069 KPa). From the resulting absorption versus time data,the characteristic time (Tau) to reach 60% of the equilibrium absorptioncapacity is determined.

Equipment & Materials

Electronic balance, accurate to 0.001 gram (200 gram minimum capacity).

Cylinder group: 1 inch (25.4 mm) inside diameter, plastic cylinder (120)with a 100 mesh stainless steel screen affixed to the cylinder bottom;4.4 gram plastic piston disk (122) with a 0.995 inch (25.27 mm)diameter. The piston disk diameter is 0.005 inch (0.13 mm) smaller thanthe inside diameter of the cylinder. See FIG. 11. 0.9% (wt/wt) NaClsolution (Blood Bank Saline).

Saline basin.

Timer (140) capable of reading 120 minutes at one second intervals.

Weighing paper.

A tapping device is positioned above the sample to provide a consistenttapping onto the supporting piston disk, as illustrated in FIGS. 10 and12. This tapping dislodges any trapped air surrounding the SAP andensures that liquid wets the SAP surface. In this setup, a motor (128)rotates a shaft which drives a rod (130) along an up and down stroke. Atthe lower end of the rod is a rubber foot (132) which has a diameter of13 mm, as illustrated in FIG. 12. The shaft stroke is 3 cm and itcompletes a full up and down stroke cycle every 0.7 seconds. The maximumpressure that the piston disk will apply to the SAP at impact is 0.16psi (0.11 KPa).

With reference to FIG. 10, a fixture (134) has a vacuum port (136) thatallows for the evacuation of interstitial liquid from the sample. Theport accommodates the base of the cylinder group. When the cylindergroup containing the sample is placed on the fixture, the free liquid isremoved from between the sample particles. A suitable pump (138) appliesa vacuum pressure applied to the sample of 100 torr (13.3 KPa) or less.

FIG. 10 shows the entire test setup. It should be noted that electronictimers (140) are desirably employed to control the duration of thetapping and vacuum devices. In this setup the tapping device also restsonto a slide (142) which would allow movement between multiple samples.

Procedure

1. Weigh out 0.160 grams (±0.001 grams) of superabsorbent onto thepre-tared weighing paper. The particle size distribution is the “asreceived” particle size distribution.

2. Slowly pour the superabsorbent into the cylinder having the 100 meshbottom. Avoid allowing the SAP to contact the sides of the cylinderbecause granules may adhere. Gently tap the cylinder until the granulesare evenly distributed on the screen.

3. Place the plastic piston in the cylinder. Weigh this cylinder groupand record the weight as the “cylinder group superabsorbent amount.”

4. Fill the saline basin to a 1 cm height with the blood bank saline.

5. Place the cylinder group in the saline basin, directly below theshaft of the tapping device and start the timer. Start and operate thetapping device to tap for an eight second cycle.

6. Five minutes after the cylinder is placed into the basin, remove thecylinder, stop the timer and place the cylinder onto the vacuumplatform, as illustrated in FIG. 14. Apply the vacuum for a 6 secondperiod.

7. Weigh the cylinder group and record the weight.

8. Return the cylinder group to the basin below the tapping device andagain start the timer. Note that the time between removing the cylindergroup from the saline in step 6 to reintroducing the cylinder group tothe saline in step 8 should not exceed 30 seconds. Repeat the initialsequence of soaking, removing, vacuuming, and weighing to gather andrecord data at cumulative soak times of 1, 5, 10, 15, 30, 45, 60, 75, 90and 120 minutes.

9. Conduct the procedure described in steps 1-8 a total of three times.

Results and Analysis

Calculate the grams of saline absorbed per gram of superabsorbentpolymer, and plot as a function of cumulative soak time.

Determine the final equilibrium absorption capacity of the SAP: If thereis less than a 5% change in the average capacity (average of threetests) of the SAP obtained at 90 and 120 minutes, then use the capacityat 120 minutes as the equilibrium capacity, FAUZL. If there is greaterthan a 5% change in the average capacity, then the sample testing willneed to be repeated and will need to include an additional sampling at acumulative soak time of 200 minutes. Use the capacity at 200 minutes asthe equilibrium capacity, FAUZL, for this latter situation.

Determine the interpolated time (Tau) to reach 60% of the equilibriumabsorption capacity. This is done by calculating the capacity at 60% ofthe equilibrium value, then estimating the correspond time to reach thiscapacity from the graph. The interpolated time to reach 60% capacity (bythis procedure), is obtained by performing a linear interpolation withthe data points that lay to either side of the estimated time.

Calculate the arithmetic average interpolated time to reach 60% of theequilibrium capacity (average of three tests). This average time valueis referred to as “Tau” (τ).

Liquid Contact Angle with Fibers

A suitable technique for measuring the liquid contact angle with a fiberis described in U.S. Pat. No. 5,364,382, the entire disclosure of whichis incorporated herein by reference in a manner that is consistentherewith. In particular, the wettability of fibers can be determinedusing contact angle measurements on fibers. Repeat cycle, single fibercontact angle measurements using distilled water can be performed with aCahn Surface Force Analyzer (SFA222) and WET-TEK data analysis software.The SFA222 is available from Cahn Instruments, Inc., of Cerritos,Calif., and the WET-TEK software is available from BiomaterialsInternational, Inc., of Salt Lake City, Utah. Fibers are tested throughthree measurement cycles, and the bath of distilled water is changedbetween cycles one and two. The liquid contact angle for the fibermaterial is determined by taking the arithmetic average of the threemeasurements. The test instrument is operated in accordance with thestandard operating techniques described in the Cahn SFA-222 SystemInstruction Manual supplied by the manufacturer.

EXAMPLES

The following Examples are presented to provide a more detailedunderstanding of the invention, and are not intended to limit the scopeof the invention. In the various examples, it should be noted that thefirst primary layer portion 48 may alternatively be referred to as thetop layer or upper layer, and that the second primary layer portion 50may alternatively be referred to as the bottom layer or lower layer.

Example 1

The upper layer is at a basis weight of 400 gsm and is composed of 20%53C superabsorbent, a superabsorbent available from Dow Chemical, and80% HPF2 mercerized pulp, a material available from Buckeye Corp. TheDow 53C superabsorbent has a τ of 8.5 minutes; a FAUZL capacity of 33g/g; and a 0.3 psi MAUL value of 26.2 g/g. The upper layer extends overthe area of the layer region 48 shown in FIG. 2, and is densified to 0.2g/cc.

The lower layer is at a basis weight of 450 gsm and is composed of 40%SXM 880 superabsorbent, a superabsorbent material available fromStockhausen, and 60% CR-1654 fluff pulp, available from Alliance ForestProducts, a company located in Coosa Pines, Ala. The SXM 880superabsorbent has a τ of 4 minutes; a FAUZL capacity of 38 g/g; and a0.3 psi MAUL value of 29.8 g/g. The lower layer extends over the entirearea of the absorbent system (the area of layer region 50), as shown inFIG. 2, and is densified to 0.2 g/cc.

This example has a Flow Conductance Value of 2.98×10⁻⁶ cm³ and a LiquidWicking Value of 41.2%.

Example 2

The upper layer is at a basis weight of 400 gsm and is composed of 20%53C superabsorbent, a superabsorbent available from Dow Chemical, 5%Type 255 binder fiber, available from Hoechst Celanese Corporation, and75% HPF2 pulp, available from Buckeye Cellulose Co. The Dow 53Csuperabsorbent has a τ of 8.5 minutes; a FAUZL capacity of 33 g/g; and a0.3 psi MAUL value of 26.2 g/g. The material was produced at a densityof 0.05 g/cc and densified for use in the product to 0.2 g/cc underconditions which would not result in the remelting and bonding of thebinder fiber. This material was shaped as shown in FIG. 2.

The lower layer is at a basis weight of 450 gsm and is composed of 40%SXM 880 superabsorbent, a superabsorbent material available fromStockhausen, and 60% CR-1654 fluff pulp, available from Alliance ForestProducts, a company located in Coosa Pines, Ala. The SXM 880superabsorbent has a τ of 4 minutes; a FAUZL capacity of 38 g/g; and a0.3 psi MAUL value of 29.8 g/g. The lower layer extends over the entirearea of the absorbent system (the area of layer 50) as shown in FIG. 2and is densified to 0.2 g/cc.

This example has a Flow Conductance Value of 2.85×10⁻⁶ cm³ and a LiquidWicking Value of 41.2%.

Example 3

The upper layer has a basis weight of 350 gsm and is composed of 40% 53Csuperabsorbent, a superabsorbent available from Dow Chemical and 60%HPF2 fluff pulp, available from Buckeye Cellulose Co. The Dow 53Csuperabsorbent has a τ of 8.5 minutes; a FAUZL capacity of 33 g/g; and a0.3 psi MAUL value of 26.2 g/g. The material is utilized in the shape ofthe layer 48, as described in FIG. 2, and has a density of 0.2 g/cc.

The lower layer is at a basis weight of 450 gsm and is composed of 40%SXM 880 superabsorbent, a superabsorbent material available fromStockhausen, and 60% CR-1654 fluff pulp, available from Alliance ForestProducts, a company located in Coosa Pines, Ala. The SXM 880superabsorbent has a τ of 4 minutes; a FAUZL capacity of 38 g/g; and a0.3 psi MAUL value of 29.8 g/g. The lower layer extends over the entirearea of the absorbent system (the area of layer 50) as shown in FIG. 2and is densified to 0.2 g/cc.

This example has a Flow Conductance Value of 4.05×10⁻⁶ cm³ and a LiquidWicking Value of 40.0%.

Example 4

The upper layer has a basis weight of 250 gsm and is composed of 67%, 1dpf PE/PP in a side by side configuration with the split of polymerbeing 50:50 and 33% 53C superabsorbent available from Dow Chemical Co.The Dow 53C superabsorbent has a τ of 8.5 minutes; a FAUZL capacity of33 g/g; and a 0.3 psi MAUL value of 26.2 g/g. The material is utilizedin the shape of the layer 48, as shown in FIG. 2, and has a density of0.060 g/cc.

The lower layer is at a basis weight of 450 gsm and is composed of 40%SXM 880 superabsorbent, a superabsorbent material available fromStockhausen, and 60% CR-1654 fluff pulp, available from Alliance ForestProducts, a company located in Coosa Pines, Ala. The SXM 880superabsorbent has a τ of 4 minutes; a FAUZL capacity of 38 g/g; and a0.3 psi MAUL value of 29.8 g/g. The lower layer extends over the entirearea of the absorbent system (the area of the layer 50) as shown in FIG.2 and is densified to 0.2 g/cc.

This example has a Flow Conductance Value of 3.37×10⁻⁶ cm³ and a LiquidWicking Value of 43.7%.

The above data can be summarized as follows:

Flow Liquid Combined Conductance Wicking Conductance- Example ValueValue Wicking Value # (×10⁻⁶ cm³) (%) (×10⁻⁶ cm³) 1 2.98 41.2 16.7 22.85 41.2 16.6 3 4.05 40   17.4 4 3.37 43.7 17.9

Some conventional absorbent structures have identified the need forimproved distribution, and other conventional structures have identifiedthe need for improved intake. Such conventional structures, however,have not been configured to provide the distinctive combination ofliquid intake and distribution provided by the various arrangements andaspects of the present invention. The following comparative Examples 5through 9 were prepared.

Upper Layer Upper Layer Lower Layer Lower Layer SAP Type Fluff Type SAPType Fluff Type Example # SAP BW Fluff BW SAP BW Fluff BW Example 5^(A)SXM 880 CR-1654 SXM 880 CR-1654 215 gsm 400 gsm 78 gsm 232 gsm Example6^(B) 20/30 SXM 870 CCLC 60/100 SXM 870 CCLC 269 gsm 292 gsm 529 gsm 294gsm Example 7^(B) SXM 870 CCLC 60/100 SXM 870 CCLC 159 gsm 295 gsm 319gsm 295 gsm Example 8^(B) 20/30 SXM 870 CCLC 60/100 SXM 870 CCLC 99 gsm281 gsm 239 gsm 281 gsm Example 9^(C) N/A CCLC SXM 880 CR-1654 300 gsm250 gsm 250 gsm ^(A)It is believed that Example 5 is representative ofthe structure taught by U.S. Pat. No. 5,356,403 to Faulks, et al. InExample 5, the upper layer had a density of 0.2 g/cc, and the lowerlayer had a density of 0.3 g/cc. ^(B)It is believed that Examples 6through 8 are representative of the structures taught by EP 0 631 768 A1of Plischke, et al.. In these examples, both layers had a density of 0.2g/cc and both layers extended over the full area of the composite padshape described in EP 0 631 768 A1. ^(C)It is believed that Example 9 isrepresentative of the structure taught by U.S. Pat. No. 5,360,420 toCook, et al.. The top layer had a density of 0.07 g/cc, and the bottomlayer had a density of 0.25 g/cc. Both layers had the shape described inU.S. Pat. No. 5,360,420.

CCLC is chemically cross-linked cellulose, as described in U.S. Pat. No.4,898,642, for example.

SXM 870 and SXM 880 are superabsorbents produced by Stockhausen underthe tradename FAVOR SX. Where indicated, the superabsorbent is sieved tothe listed particle size in mesh; e.g. 20/30 mesh (600 to 850 μm),60/100 mesh (150 to 250 elm). The SXM 880 superabsorbent has a τ of 4minutes; a FAUZL capacity of 38 g/g; and a 0.3 psi MAUL value of 29.8g/g.

The SXM 870 superabsorbent has a τ of 4 minutes; a FAUZL capacity of32.5 g/g; and a 0.3 psi MAUL value of 27 g/g.

The “20/30 SXM 870” superabsorbent has a τ of 6.4 minutes; a FAUZLcapacity of 34 g/g; and a 0.3 psi MAUL value of 28.8 g/g.

The “60/100 SXM 870” superabsorbent has a τ of 3.3 minutes; a FAUZLcapacity of 27.5 g/g; and a 0.3 psi MAUL value of 25.3 g/g.

Examples 5-9 exhibited the characteristics set forth in the followingTable.

Flow Liquid Combined Conductance Wicking Conductance- Value ValueWicking Value Example (×10⁻⁶ cm³) (%) (×10⁻⁶ cm³) 5 2.9  31.7 13.5 66.75 13.3 11.2 7 6.75 13.4 11.2 8 6.68 20.8 13.6 9 1.4  35.2 13.1

As can be seen, the structures of these examples do not provide thecombination of characteristics afforded by the structures of the presentinvention.

Examples 10-11

For Examples 10 and 11, two-layer absorbent composite structures wereconstructed in accordance with the following Table:

Upper Layer 200 g/m² of Stockhausen W52521 superabsorbent; and 133 g/m²of woodpulp fluff. Lower Layer 239 g/m² of Stockhausen Favor 870superabsorbent; and 281 g/m² of woodpulp fluff.

The woodpulp fluff set forth in Table 1 had the designation CR-1654,which is available from Alliance Forest Products, a company located inCoosa Pines, Ala.

In both layers, the superabsorbent was uniformly mixed with the woodpulpfluff. Both the upper layer and lower layer had a density of 0.2 g/cm³,and both layers extended over the entire composite pad. The compositepad employed the pad shapes described in EP 0 631 768 of Plischke, etal.

In Example 10, the Stockhausen W52521 superabsorbent was employed in itsas-received condition, as supplied by Stockhausen, Inc. The as-receivedW52521 superabsorbent had a τ value of 4 minutes.

The two-layer absorbent structure constructed for Example 10 had thefollowing properties:

Upper Layer with W52521 superabsorbent material; Liquid wicking value1.4%.

Lower Layer with 870 superabsorbent material; Liquid wickingvalue=13.3%.

Accordingly, the Liquid Wicking value for the two-layer composite wasthe 13.3%.

In Example 11, the Stockhausen W52521 superabsorbent was sievedemploying U.S. Standard Testing Sieves, and the sieved superabsorbenthad a resulting size fraction of 500-710 microns. The sieved W52521superabsorbent had a τ value of 6.8 minutes.

The two-layer absorbent structure constructed in Example 11 had thefollowing properties:

Upper Layer with W52521 superabsorbent material (500-710 micron,particle size);

Liquid wicking value=0.9%.

Lower Layer with 870 superabsorbent material; Liquid wicking value=9.9%.

Accordingly, the Liquid Wicking value for the two-layer composite wasthe 9.9%.

As can be seen, the structures of Examples 10 and 11 do not provide theproperties afforded by the structures of the present invention.

Having described the invention in rather full detail, it will be readilyapparent that various changes and modifications can be made withoutdeparting from the spirit of the invention. All of such changes andmodifications are contemplated as being within the scope of theinvention.

We claim:
 1. An absorbent article, comprising: a backsheet layer; asubstantially liquid permeable topsheet layer; and an absorbentcomposite structure sandwiched between said backsheet and topsheetlayers, said absorbent composite including an absorbent core having afirst, superabsorbent containing, fibrous primary layer region and atleast a second, superabsorbent containing, fibrous primary layer region;wherein at least one of said first and second primary layer regions hasa Liquid Wicking Value of at at least one of said primary layer regionsincludes a superabsorbent material which exhibits a Tau value of notless than about 0.8 min.
 2. An article as recited in claim 1, whereinsaid absorbent core has a dry thickness of not more than about 6 mm, anda minimum crotch width of not more than about 10 cm.
 3. An article asrecited in claim 1, wherein said article is configured for use by anadult, and wherein said absorbent core has a dry thickness of not morethan about 6 mm, and a minimum crotch width of not more than about 14cm.
 4. An article as recited in claim 1, wherein said first primarylayer region is located on a bodyside of the absorbent composite, andsaid second primary layer region is located relatively outward from saidfirst layer region.
 5. An absorbent article as recited in claim 1,wherein at least one of said primary layer regions includes asuperabsorbent material having a Modified Absorbency Under Load value ofat least about 20 g/g.
 6. An article as recited in claim 1, wherein saidfirst primary layer region includes a first superabsorbent having afirst Tau value; said second primary layer region includes a secondsuperabsorbent having a second Tau value; and said first Tau value isgreater than said second Tau value.
 7. An article as recited in claim 6,wherein said first primary layer region is positioned at a bodyside ofsaid absorbent core; and a ratio of said first Tau value to said secondTau value is at least about 2:1.
 8. An article as recited in claim 7,wherein said ratio of said first Tau value to said second Tau value isat least about 5:1.
 9. An absorbent article, comprising: a backsheetlayer; a substantially liquid permeable topsheet layer; and an absorbentsystem sandwiched between said backsheet and topsheet layers, saidabsorbent system including an absorbent core having a first,superabsorbent containing, fibrous primary layer region and at least asecond, superabsorbent containing, fibrous primary layer region; whereinsaid absorbent core has a combined Conductance-Wicking Value of at leastabout at least one of said primary layer regions includes asuperabsorbent material which exhibits a Tau value of not less thanabout 0.8 min.
 10. An article as recited in claim 9, wherein saidabsorbent core has a dry thickness of not more than about 6 mm and aminimum crotch width of not more than about 10 cm.
 11. An absorbentarticle which includes an absorbent core having a first, superabsorbentcontaining, fibrous primary layer region and at least a second,superabsorbent containing, fibrous primary layer region; wherein saidabsorbent core has a longitudinal length, a lateral width and anappointed front-most edge; said first primary layer region has a basisweight of not less than about 100 g/m² and not more than about 500 g/m²;said first primary layer region has a first layer region density of notless than about 0.03 g/cm³ and not more than about 0.4 g/cm³; said firstprimary layer region includes fibrous material in an amount which is notless than about 25 wt % and is not more than about 80 wt %; said fibrousmaterial includes fibers having fiber sizes which are not less thanabout 4 μm and not more than about 20 μm; said fibrous material includesfibers which exhibit a water contact angle of not more than about 65degrees; said first primary layer region includes a superabsorbentmaterial in an amount which is not less than about 20 wt % and is notmore than about 75 wt %; said superabsorbent material in said firstprimary layer includes superabsorbent particles having particle sizeswhich are not less than about 140 μm and are not more than about 1000μm; said superabsorbent material in said first primary layer has a MAULvalue of not less than about 20 g/g; said superabsorbent material insaid first primary layer has a Tau value of not less than about 0.8 min;and said first primary layer region has a Liquid Wicking Value of atleast about 36%.
 12. An article as recited in claim 11, wherein saidfirst primary layer region is substantially coterminous with side edgesof said second primary layer region; and said first primary layer regioncontained within a zone which begins at a laterally extending linepositioned about 7% of the core length inboard from said front-most edgeof the absorbent core and extends to a laterally extending linepositioned about 62% of the core length inboard from said front-mostedge of the absorbent core.
 13. An article as recited in claim 12,wherein said first primary layer region includes a binder material. 14.An article as recited in claim 11, wherein said first primary layerregion includes a plurality of sublayers.
 15. An article as recited inclaim 11, wherein said second primary layer region has a longitudinalextent which is greater than a longitudinal extent of said first primarylayer region; and said second primary layer region has a lateral extentwhich is substantially coterminous with said first primary layer region.16. An article as recited in claim 11, wherein said second primary layerregion has a longitudinal extent which is greater than a longitudinalextent of said first primary layer region; said second primary layerregion has a lateral extent which is less than a lateral extent of saidfirst primary layer region; and a lateral extent of at least a portionof said second primary layer region is not less than about 30% of alateral extent of a correspondingly adjacent portion of said firstprimary layer region.
 17. An article as recited in claim 11, whereinsaid second primary layer region has a longitudinal extent which isgreater than a longitudinal extent of said first primary layer region;said second primary layer region has a lateral extent which is greaterthan a lateral extent of said first primary layer region; a lateralextent of at least a portion of said first primary layer region is notless than about 30% of a lateral extent of a correspondingly adjacentportion of said second primary layer region.
 18. An article as recitedin claim 17, wherein said second primary layer region has asubstantially uniform basis weight.
 19. An article as recited in claim11, wherein said second primary layer region has a basis weight which isnot less than about 300 g/m² and is not more than about 700 g/m²; saidsecond primary layer region has a second layer region density of notless than about 0.1 g/cm³ and not more than about 0.3 g/cm³; said secondprimary layer region includes fibrous material in an amount which is notless than about 50 wt % and is not more than about 80 wt %; said fibrousmaterial includes fibers having fiber diameters which are not less thanabout 4 μm and not more than about 20 μm; said fibrous material includesfibers which exhibit a water contact angle of not more than about 65degrees; said second primary layer region includes a superabsorbentmaterial in an amount which is not less than about 20 wt % and is notmore than about 50 wt %; and said superabsorbent material includessuperabsorbent particles having particle sizes which are not less thanabout 140 μm, and are not more than about 1000 μm.
 20. An article asrecited in claim 19, wherein said superabsorbent material in said secondprimary layer region has a MAUL value of not less than about 20 g/g, andhas a Tau value of at least about 0.4 minutes.
 21. An article as recitedin claim 20, wherein said superabsorbent material in said second primarylayer region is configured as a layer laminated between tissue layers.22. An article as recited in claim 21, wherein said article furthercomprises a backsheet layer and a substantially liquid permeabletopsheet layer which are configured with said absorbent core sandwichedtherebetween.
 23. An article as recited in claim 22, wherein saidabsorbent core has a Flow Conductance Value of at least about 7*10⁻⁶cm³.
 24. An article as recited in claim 23, wherein said second primarylayer region includes a binder material.
 25. An article as recited inclaim 19, wherein said absorbent core has a dry thickness of not morethan about 6 mm, and a minimum crotch width of not more than about 10cm.
 26. An article as recited in claim 19, wherein said article isconfigured for use by an adult, and wherein said absorbent core has adry thickness of not more than about 6 mm, and a minimum crotch width ofnot more than about 14 cm.
 27. An article as recited in claim 19,wherein said absorbent core has a Flow Conductance Value of at leastabout 7*10⁻⁶ cm³.
 28. An article as recited in claim 27, wherein saidabsorbent core has a Conductance-Wicking Value of at least about 14*10⁻⁶cm³.
 29. An article as recited in claim 19, wherein said absorbent corehas a Conductance-Wicking Value of at least about 14*10⁻⁶ cm³.
 30. Anarticle as recited in claim 11, wherein said first primary layer regionis positioned at a bodyside of said absorbent core; said first primarylayer region includes a first superabsorbent having a first Tau value;said second primary layer region includes a second superabsorbent havinga second Tau value; and a ratio of said first Tau value to said secondTau value is at least about 2:1.
 31. An article as recited in claim 30,wherein said ratio of said first Tau value to said second Tau value isat least about 5:1.